Weight Loss Provider Guide · Calculator
GLP-1 Weight Loss Calculator: Wegovy, Zepbound & Foundayo (2026)
Anchored to FDA-label trial data. Mean loss ranges from 5% to 21% depending on medication, dose, and diabetes status.
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FDA-approved for chronic weight management
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6
medications
18
month chart
FDA
trial data
Trajectory
Weight over 18 months on Wegovy
Month 1
6 lbs
appetite shifts
Month 3
16 lbs
first clothing size
Month 6
24 lbs
BMI category shift
Month 12
30 lbs
approaching maintenance
- FDA-label data
- No email required
- Private estimate
- Clinician review required
By WPG Research Team · · Next review: August 2026
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How much weight can you lose on a GLP-1?
The short version: FDA-approved weight-management GLP-1 and GIP/GLP-1 medicines show mean endpoint losses of about 7% to 21% in adults without type 2 diabetes, and about 5% to 15% in adults with type 2 diabetes, depending on medication and dose. Tirzepatide (the drug in Zepbound and Mounjaro) usually produces higher average loss than semaglutide (the drug in Wegovy and Ozempic) at top dose because it activates two hormone pathways instead of one.
Every percentage in the table below comes from the FDA-approved prescribing information for that drug. These are the label's endpoint estimates for the study population shown.
| Drug + Dose | Approved for | Mean loss (no T2D) | Mean loss (T2D) | Trial | Endpoint |
|---|---|---|---|---|---|
| Wegovy 2.4mg (injection) | Weight management | 14.9% | 9.6% | STEP 1 / STEP 2 | 68 weeks |
| Wegovy HD 7.2mg | Weight management | 18.8% | 13.2% | STEP UP | 72 weeks |
| Wegovy 25mg tablet | Weight management | 13.6% | — | OASIS-4 | 64 weeks |
| Zepbound 5mg | Weight management | 15.0% | — | SURMOUNT-1 | 72 weeks |
| Zepbound 10mg | Weight management | 19.5% | 12.8% | SURMOUNT-1 / SURMOUNT-2 | 72 weeks |
| Zepbound 15mg | Weight management | 20.9% | 14.7% | SURMOUNT-1 / SURMOUNT-2 | 72 weeks |
| Foundayo 5.5mg (oral, daily) | Weight management | 7.4% | 5.1% | ATTAIN-1 / ATTAIN-2 | 72 weeks |
| Foundayo 9mg (oral, daily) | Weight management | 8.3% | 7.0% | ATTAIN-1 / ATTAIN-2 | 72 weeks |
| Foundayo 17.2mg (oral, daily) | Weight management | 11.1% | 9.6% | ATTAIN-1 / ATTAIN-2 | 72 weeks |
| Ozempic 1mg | Type 2 diabetes (off-label for weight) | — | ~6% | SUSTAIN | 40 weeks |
| Ozempic 2mg | Type 2 diabetes (off-label for weight) | — | ~7% | SUSTAIN FORTE | 40 weeks |
| Mounjaro 10mg | Type 2 diabetes (off-label for weight) | — | ~9% | SURPASS | 40 weeks |
| Mounjaro 15mg | Type 2 diabetes (off-label for weight) | — | ~12% | SURPASS | 40 weeks |
| Compounded semaglutide | Not FDA-approved as finished product | Not modeled as FDA-label equivalent | — | — | — |
| Compounded tirzepatide | Not FDA-approved as finished product | Not modeled as FDA-label equivalent | — | — | — |
Sources: FDA-approved prescribing information for Wegovy and Zepbound; FDA Foundayo approval; published SUSTAIN and SURPASS trial data. Verified May 7, 2026. T2D = type 2 diabetes.
Why dose matters more than most articles say
Most calculators on the internet just multiply your weight by one number per drug. That's not how the trials worked. Zepbound 5mg averaged 15.0% loss. Zepbound 15mg averaged 20.9%. That's a 5.9 percentage-point gap on the same drug. For a 220-lb adult, the difference is about 13 pounds.
Most people don't start at top dose. You titrate up — meaning your clinician slowly increases the dose every 4 weeks to let your body adjust. Some people stop at 5mg or 10mg because of side effects. Your real-world result depends on how high you can comfortably go.
Why semaglutide and tirzepatide aren't the same drug
Semaglutide activates one hormone receptor — GLP-1, short for glucagon-like peptide-1 (a hormone your gut makes that tells your brain you're full). Wegovy and Ozempic both contain semaglutide.
Tirzepatide activates two receptors — GLP-1 plus GIP, short for glucose-dependent insulinotropic polypeptide (a second gut hormone with related effects). Zepbound and Mounjaro both contain tirzepatide.
Orforglipron (Foundayo) is a once-daily oral GLP-1 receptor agonist — the first non-peptide oral option in this class. It's swallowed, not injected. Hitting two pathways instead of one is part of why Zepbound usually beats Wegovy in head-to-head averages. It doesn't mean tirzepatide is right for everyone. Side effects, cost, and access matter just as much.
Why the placebo group lost weight too
Even people getting a placebo lost weight in these trials, because every trial included diet and exercise counseling. Wegovy STEP 2 placebo arm lost about 2.4% at 68 weeks. The Zepbound SURMOUNT-1 placebo arm lost about 3.1% at 72 weeks. Foundayo ATTAIN-1 placebo arm lost about 2.1% at 72 weeks. The medication-attributable weight loss is the gap between your projection and the matching placebo number — for a 220-lb adult on Zepbound 15mg, that's roughly 39 lbs of drug-driven loss.
How much will you lose at your starting weight?
Trial percentages translate into different pound-numbers depending on where you start. A 14.9% loss is 22 lbs at 150 lb — but 45 lbs at 300 lb. The table below converts FDA-label averages into real-life numbers. These are averages, not guarantees.
| Starting weight | Wegovy 2.4mg (no T2D) | Wegovy 2.4mg (T2D) | Zepbound 10mg (no T2D) | Zepbound 15mg (no T2D) | Foundayo 17.2mg (no T2D) |
|---|---|---|---|---|---|
| 150 lb | ~22 lb | ~14 lb | ~29 lb | ~31 lb | ~17 lb |
| 180 lb | ~27 lb | ~17 lb | ~35 lb | ~38 lb | ~20 lb |
| 200 lb | ~30 lb | ~19 lb | ~39 lb | ~42 lb | ~22 lb |
| 220 lb | ~33 lb | ~21 lb | ~43 lb | ~46 lb | ~24 lb |
| 250 lb | ~37 lb | ~24 lb | ~49 lb | ~52 lb | ~28 lb |
| 300 lb | ~45 lb | ~29 lb | ~59 lb | ~63 lb | ~33 lb |
| 350 lb | ~52 lb | ~34 lb | ~68 lb | ~73 lb | ~39 lb |
Math: starting weight × FDA-label mean endpoint percentage. T2D = type 2 diabetes. Use the calculator above for a personalized 3-, 6-, 12-, and 18-month projection.
Why type 2 diabetes lowers the average
If you have type 2 diabetes, you'll likely lose less weight on the same dose of the same drug. The FDA-label tables show this consistently: Wegovy 2.4mg in non-diabetic obesity averaged 14.9% at 68 weeks; in type 2 diabetes, 9.6%. Zepbound 15mg in non-diabetic obesity averaged 20.9% at 72 weeks; in type 2 diabetes, 14.7%. Foundayo 17.2mg follows the same pattern: 11.1% without T2D, 9.6% with. If you have diabetes, plan around the diabetes-trial averages. Then talk to your clinician about a path that handles weight and blood sugar together.
Why your real number probably won't be the average
The "average" hides a wide spread. In SURMOUNT-1, about half of people on Zepbound 10mg lost more than 20%. About one in nine lost less than 5%. Two people at the same weight on the same dose can land 30 lbs apart at the trial endpoint. That's normal. The calculator gives you the middle of the curve. Where you actually land depends on factors no calculator can predict.
Which GLP-1 should you compare for your goal?
The short version: Match the drug to the goal. If your goal is more than 15% body weight loss, Zepbound (tirzepatide) clears that bar more often. If your goal is 10–14%, Wegovy is a strong match and is sometimes lower-cost. If your goal is around 7–11%, Foundayo is the only oral FDA-approved option in 2026. If you have type 2 diabetes, the path is different and a clinician should drive the choice.
If your goal is 15%+ body weight loss
Wegovy 2.4mg averages 14.9% at the trial endpoint. So a goal above 15% is at the edge of Wegovy's reach. Zepbound 15mg averages 20.9%. Wegovy HD 7.2mg averages 18.8%. Both clear a 15% goal more reliably. If your goal needs that ceiling, the FDA-label Zepbound and Wegovy HD lanes match more often than the Wegovy 2.4mg lane.
If your goal is 10–14%
Wegovy 2.4mg averages 14.9%. That's right in the pocket. Cash-pay Wegovy through NovoCare is $349 per month after a $199 introductory rate for the first two months. The Wegovy 25mg tablet averaged 13.6% in OASIS-4 — also in range. Compounded semaglutide can run lower in price, but quality, dosing accuracy, and legal status vary by pharmacy.
If your goal is around 7–11% (or you want an oral option)
Foundayo (orforglipron) is the first FDA-approved once-daily oral GLP-1 for weight management. The 17.2mg dose averaged 11.1% at 72 weeks; 9mg averaged 8.3%. If you want results without injections — and you're not chasing a 20% drop — this lane is new in 2026 and worth comparing. FDA approval announcement, April 2026.
If you have type 2 diabetes
GLP-1s can do double duty in diabetes — they help blood sugar and weight together. But the weight-loss numbers are lower than the obesity-only averages, and managing both at once needs a clinician's input on dose, other diabetes meds, and timing. The path here is clinician-first. A calculator can give you a planning estimate. It can't manage your A1C.
If you have commercial insurance
For eligible commercially insured patients, manufacturer savings cards can bring Wegovy or Zepbound as low as $25 per month, subject to program rules and maximum savings limits. Federal law blocks this for anyone on Medicare, Medicaid, TRICARE, or VA coverage. If your plan covers GLP-1s for weight management, this is usually the cheapest legal path. Call your plan or use the manufacturer's coverage lookup tool — don't assume.
If you're on Medicare
Medicare Part D has historically excluded weight-loss medication coverage, but two pathways are changing that in 2026:
The Zepbound obstructive sleep apnea (OSA) pathway. Zepbound is FDA-approved for moderate-to-severe OSA in adults with obesity. Medicare Part D can cover it for that indication if you have documented OSA.
The Medicare GLP-1 Bridge. CMS announced on May 6, 2026 that beginning July 1, 2026, eligible Part D-enrolled beneficiaries can access Foundayo, Wegovy, or Zepbound at $50 per month. Eligibility includes BMI ≥35, or BMI ≥30 with qualifying conditions, or BMI ≥27 with prediabetes, prior heart attack, prior stroke, or symptomatic peripheral artery disease.
What does a GLP-1 actually cost per pound lost?
The short version: A 12-month course of an FDA-approved GLP-1 costs about $3,000 to $5,200 in cash without insurance, working out to roughly $107 to $156 per pound of projected weight loss. With commercial insurance plus a manufacturer savings card, the same course can drop to about $300 a year — $7 to $15 per pound. The verified table below uses May 2026 manufacturer pricing.
| Path (cash pay) | 12-mo projected loss (220 lb baseline) | 12-mo cash cost | Cost per pound lost |
|---|---|---|---|
| Wegovy 2.4mg (NovoCare) | ~30 lb | ~$3,888 | ~$130/lb |
| Wegovy HD 7.2mg (NovoCare) | ~38 lb | ~$4,388 | ~$116/lb |
| Wegovy 25mg tablet (NovoCare) | ~28 lb | ~$2,988 | ~$107/lb |
| Zepbound 5mg vial (LillyDirect) | ~30 lb | ~$4,688 | ~$156/lb |
| Zepbound 10mg vial (LillyDirect) | ~39 lb | ~$5,188 | ~$133/lb |
| Zepbound 15mg vial (LillyDirect) | ~42 lb | ~$5,188 | ~$124/lb |
| Foundayo 17.2mg (LillyDirect) | ~22 lb | ~$3,338 | ~$152/lb |
| TrumpRx (federal program) | varies | ~$4,152–$4,200 | varies |
| Insurance + manufacturer savings card | varies | ~$300/yr ($25 × 12) | ~$7–$15/lb |
| Medicare GLP-1 Bridge (July 2026+) | varies | ~$600/yr ($50 × 12) | ~$14–$27/lb |
| Compounded semaglutide (typical $200/mo) | — | ~$2,400 | Pricing varies — verify with pharmacy |
| Lifestyle alone | ~5–7 lb | $0 | $0 |
Cost figures use manufacturer primary-source cash pricing programs: NovoCare for Wegovy; LillyDirect Self-Pay Journey for Zepbound and Foundayo. Verified May 7, 2026. 12-month projected loss uses our calculator's logarithmic curve, not the trial endpoint number (trial endpoints are 64–72 weeks).
The 45-day refill rule on Zepbound and Foundayo
Lilly's Self-Pay Journey program for higher-dose Zepbound vials (7.5mg, 10mg, 12.5mg, and 15mg) locks in the lower price only if you refill within 45 days of your previous delivery. If the purchase offer doesn't apply, regular price kicks in. Foundayo's higher doses (14.5mg, 17.2mg) follow a similar pattern: $299/month with 45-day refill discipline, $349/month if you fall off the cadence. A 220-lb adult on Zepbound 15mg who misses two refills could easily pay $5,800 or more for the year.
What about TrumpRx?
In November 2025, the White House announced agreements with Eli Lilly and Novo Nordisk to offer certain GLP-1 medicines through TrumpRx. Novo will offer Ozempic and Wegovy at $350/month through TrumpRx; Lilly will offer Zepbound and orforglipron at an average monthly price of $346. Verify availability at trumprx.gov before relying on it; rollout has been gradual.
Month-by-month: when does the weight come off?
The short version: Most weight loss happens in months 3 through 9. Trial data shows about 2–4% body-weight loss by month 1, around 8% by month 3, 13–15% by month 6, and 14–22% by month 12 depending on drug and dose. Most people approach plateau between months 9 and 12.
Weeks 1–4 (titration begins). You start at the lowest dose. Most people see 2–4% body weight loss by the end of month 1. Some of that is water weight from eating less. Your appetite changes faster than the scale.
Months 2–3 (steady ramp). You step up doses every 4 weeks if you can tolerate it. By the end of month 3, average loss is around 6–10% of starting body weight. For a 220-lb adult, that's about 13–22 lbs.
Months 4–9 (the steepest part of the curve). Most of your total weight loss happens in this window. By month 6, average loss is typically 13–15% on Wegovy or 14–17% on Zepbound. By month 9, you're approaching the trial endpoint.
Months 9–12 (approaching plateau). Loss slows. Your body is settling into a new normal. By month 12, most people are within 90% of their final endpoint number.
Beyond 12 months. The STEP 5 long-term Wegovy data showed weight loss continued slowly out to year 2 — total loss reached about 15.2% at 104 weeks. After that, maintenance is the goal. If you stop the medication, you're likely to regain — the STEP 1 trial extension showed people who stopped semaglutide regained roughly two-thirds of their prior weight loss within a year. GLP-1s are designed for long-term use, not 6-month sprints.
Are you eligible? BMI screening criteria explained
The short version: Common prescribing criteria for FDA-approved GLP-1 weight management start at BMI of 30 or higher, or BMI of 27 or higher with a weight-related condition. These are screening thresholds clinicians use — only a licensed clinician can decide if treatment is right for you.
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25.0–29.9 | Overweight |
| 30.0–34.9 | Obesity Class I |
| 35.0–39.9 | Obesity Class II |
| 40.0+ | Obesity Class III |
What counts as a weight-related condition
Common ones include high blood pressure (hypertension), high cholesterol (dyslipidemia), sleep apnea (obstructive sleep apnea), type 2 diabetes, cardiovascular disease, polycystic ovary syndrome (PCOS), and non-alcoholic fatty liver disease. If you have one of these and your BMI is 27–29.9, you may fall within common screening criteria. A clinician will review your full history to confirm.
Why we say "may fall within screening criteria" instead of "you qualify"
Eligibility for a GLP-1 isn't just BMI. It depends on your other medications, contraindications (such as personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia type 2 — both appear in FDA boxed warnings), pregnancy status, lab work, insurance rules, and clinician judgment. A calculator can show you whether your BMI lands inside common thresholds. It can't decide you qualify. Only a licensed clinician can.
What if you don't respond to a GLP-1?
The short version: In the main no-T2D injection trials, about 9% to 17% of trial participants didn't reach 5% loss at the endpoint. The rate is higher in some oral and type 2 diabetes lanes — Foundayo's no-T2D high-dose lane shows about 29% didn't reach 5%. Many clinicians reassess after 3–4 months on a therapeutic dose and consider next steps if results don't justify the cost and side effects.
| Trial lane | % who did NOT reach 5% loss |
|---|---|
| Wegovy 2.4mg, no T2D | ~17% |
| Wegovy 2.4mg, T2D | ~33% |
| Zepbound 5mg, no T2D | ~15% |
| Zepbound 10mg, no T2D | ~11% |
| Zepbound 15mg, no T2D | ~9% |
| Zepbound 10mg, T2D | ~21% |
| Zepbound 15mg, T2D | ~17% |
| Foundayo 17.2mg, no T2D | ~29% |
| Foundayo 17.2mg, T2D | ~33% |
Why some people don't respond: The honest answer is we don't fully know. Research suggests genetic factors, gut microbiome differences, prior dieting history, and metabolic adaptation all play roles. Some people respond beautifully to semaglutide and barely respond to tirzepatide. There's no test that predicts this in advance — you find out by trying.
Switching from semaglutide to tirzepatide (or back) is common. If Wegovy doesn't work or you can't tolerate it, switching to Zepbound is a typical next step. Your clinician handles the switch and the new titration plan. Don't switch drugs or restart at an old dose on your own.
When to stop entirely: If you've reached top dose, given it 4–6 months, and haven't hit 5% loss, the math probably isn't working. Continuing to spend hundreds of dollars a month on a drug that isn't moving the needle isn't a sound bet. Talk to your clinician about other paths.
A few words on Ozempic, Mounjaro, compounded GLP-1s, and retatrutide
Ozempic and Mounjaro are diabetes drugs
Ozempic's official site says directly: "Ozempic is not a weight-loss drug." Mounjaro's official site describes it as used for type 2 diabetes, not weight management. Yes, doctors prescribe both off-label for weight loss, and yes, they work. But the trial data behind the weight-loss numbers comes from diabetic populations on the same molecules — populations that lose less weight on average than non-diabetic populations on the weight-management brands. If a calculator shows you "lose 20%+ on Mounjaro" for weight loss, it's probably borrowing tirzepatide obesity-trial data from the Zepbound evidence base, not Mounjaro's actual diabetes-indication data.
If you're choosing for weight loss, the FDA-approved weight-management brands are Wegovy (semaglutide), Zepbound (tirzepatide), and Foundayo (orforglipron).
Compounded GLP-1s are not "generic Wegovy"
The FDA has been blunt on this. Compounded drugs are not FDA-approved finished products. The FDA has issued warning letters to compounding companies for marketing compounded GLP-1s as "generic" versions — claims the FDA flags as not accurate. Quality, dosing accuracy, and legal status vary by pharmacy. The legal landscape is shifting fast as the FDA responds to the boom. If you go compounded, verify the prescriber, the pharmacy license, the medication source, the dosing instructions, and the current legal status of that specific compound.
Retatrutide is not available
Retatrutide is a triple-receptor agonist in late-stage Lilly trials. It's shown remarkable trial results in early data. It is not FDA-approved and not available outside clinical trials. Lilly states it is investigational. The FDA has stated retatrutide and cagrilintide cannot be used in compounding under federal law. If you see a calculator that lets you pick "retatrutide" as a real option, that calculator is misleading you.
Side effects, risks, and what could go wrong
The short version: The most common GLP-1 side effects are gut-related: nausea, vomiting, diarrhea, constipation, and indigestion. They typically appear during dose escalation and may ease over time. Serious but rare risks include pancreatitis, gallbladder disease, and (in rodent studies) thyroid tumors. Wegovy and Zepbound both carry FDA boxed warnings about medullary thyroid carcinoma (MTC) and Multiple Endocrine Neoplasia syndrome type 2 (MEN2).
Common side effects (>5% of users)
- Nausea (the most common — up to half of users at some point)
- Diarrhea
- Vomiting
- Constipation
- Indigestion or stomach pain
- Fatigue
- Headache
Less common but serious
- Pancreatitis (severe abdominal pain — call your doctor)
- Gallbladder problems (gallstones, inflammation)
- Severe gastrointestinal reactions (rare)
- Low blood sugar if on insulin or sulfonylurea
- Kidney problems from severe dehydration
Boxed warnings
The boxed warning is the FDA's strongest. Wegovy and Zepbound both carry one related to thyroid C-cell tumors observed in rodent studies. They're contraindicated if you or a close family member has had medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). If those terms describe your family history, this isn't your medication — review the full prescribing information and talk to your clinician.
Why this calculator doesn't do dose math
The FDA has reported dosing errors with compounded injectable semaglutide — including overdoses where patients confused milligrams, milliliters, and "units," some serious enough to require hospitalization. Combining a weight-loss projection with dose math creates risk we won't take with our readers. If you're on compounded medication, get your dosing instructions in writing from your prescriber, not from any online calculator.
How accurate is this GLP-1 weight loss calculator?
The short version: A trial-anchored calculator gives you a reasonable expected value with a defensible range. It can't predict your individual response. About 9–17% of trial participants in the main no-T2D injection trials don't reach 5% loss; some oral and T2D lanes are higher. Treat the projection as a planning estimate, not a guarantee.
What this calculator does well
- Translates trial percentages into your real pound numbers
- Shows a planning range around the FDA-label mean
- Differentiates between drugs and doses
- Adjusts for type 2 diabetes status
- Maps your projection across 3, 6, 12, and 18 months
- Shows your projected BMI category change
What no calculator can know
- Whether you'll tolerate the medication
- Whether you'll reach maintenance dose
- Whether your prescriber will approve treatment
- Whether your insurance will cover it
- Whether you'll land above or below the trial mean
- Whether you'll keep the weight off after stopping
Red flags in other GLP-1 calculators
Watch out for calculators that:
- Promise a guaranteed result
- Hide their data sources
- Mix brand-name and compounded results without disclosure
- Call compounded products "generic Wegovy" or "generic Zepbound"
- Include retatrutide as if it were an available option
- Calculate injection units or doses
- Require an email before showing your estimate
- Show one number without a range
- Don't update for current pricing or program changes
How this GLP-1 weight loss calculator works
We built this from FDA-approved prescribing information for Wegovy, Zepbound, and Foundayo, manufacturer cash-pay pricing pages, and a transparent projection method that converts average percentage loss into a user-specific range. We don't take payment from any drug company. We earn affiliate commissions from telehealth providers featured in our quiz, which doesn't affect any number on this page.
The math behind your projection
Each drug-dose combination has three reference numbers anchored to its FDA label: a low, mean, and high percentage of body-weight loss. We apply those to your starting weight and distribute the result over time using a logarithmic curve calibrated to the drug's plateau timing.
The formula: progress(weeks) = 1 − exp(−3 × weeks ÷ plateauWeeks)
In plain English: most loss happens in the first 9–12 months, then it tapers off. The curve approximates the endpoint and time-course patterns reported in trial extension data. The "trial responder range" is a modeled planning range around the FDA-label mean — not a percentile prediction.
What we used
- Trial efficacy: FDA-approved prescribing information for Wegovy (semaglutide 2.4mg, 7.2mg HD, and 25mg tablet); FDA-approved prescribing information for Zepbound (tirzepatide 5mg, 10mg, 15mg); FDA prescribing information for Foundayo (orforglipron). Cross-referenced against published STEP, SURMOUNT, SUSTAIN, SURPASS, and ATTAIN trial data.
- Cash-pay pricing: Manufacturer primary sources — NovoCare (Novo Nordisk products) and LillyDirect (Eli Lilly products), verified May 7, 2026.
- Off-label drugs (Ozempic, Mounjaro): Trial data from SUSTAIN, SURPASS, and SURMOUNT-2 with explicit off-label flagging.
What we verified for this page (May 7, 2026)
- ✓Every drug-dose efficacy figure against the FDA-approved prescribing information
- ✓Every cash-pay price against the manufacturer's primary source
- ✓Every clinical trial citation against published primary endpoint data
- ✓Every regulatory caveat (compounded status, off-label use, retatrutide investigational status, Medicare GLP-1 Bridge eligibility, TrumpRx pricing) against current FDA, CMS, or official statements
Privacy note
Weight, BMI, type 2 diabetes status, and goal weight are health-related information. The calculator is designed to minimize data exposure by using bucketed values (for example, "BMI 30–35" rather than your exact number) when handing off to the Find My GLP-1 Path quiz. The FTC has clarified that health information includes data that enables inferences about a person's health, and we treat your inputs accordingly.
Editorial accountability
All trial percentages and methodology choices are reviewed by the Weight Loss Provider Guide research team on a quarterly cadence and within 30 days of any new Phase 3 publication or FDA action affecting an in-scope drug. Corrections are tracked publicly on our Corrections Policy page. If you spot an error in a trial figure or a dose tier, please email [email protected].
Last data review: by the Weight Loss Provider Guide research team.
Frequently asked questions
The questions readers most often ask about GLP-1 weight loss calculators and these medications.
What is a GLP-1 weight loss calculator?
A GLP-1 weight loss calculator estimates how much weight you might lose over time on a GLP-1 medication based on your starting weight, height, the specific drug and dose, and clinical-trial averages. It's a planning tool — not a prescription, not a guarantee.
How much weight can you lose in 3 months on a GLP-1?
About 6–10% of your starting body weight, based on STEP-1 and SURMOUNT-1 trial data. For a 220-lb adult, that's roughly 13–22 lbs. The exact number depends on the drug, the dose, and how fast you titrate up.
How much weight can you lose in 6 months on a GLP-1?
Around 13–15% on Wegovy 2.4mg, or 14–17% on Zepbound 10–15mg, or 7–9% on Foundayo, based on extension trial data. For a 220-lb adult, that's roughly 15–37 lbs depending on drug and dose.
How much weight can you lose in 12 months on a GLP-1?
Most users at maintenance dose are within 90% of the trial endpoint by month 12. Wegovy 2.4mg averages around 14% body weight at 12 months; Zepbound 15mg averages around 19%; Foundayo 17.2mg averages around 10%. For a 220-lb adult: roughly 22 lbs (Foundayo) to 30 lbs (Wegovy) to 42 lbs (Zepbound 15mg).
Is tirzepatide better than semaglutide for weight loss?
In separate FDA-label trials, tirzepatide (Zepbound 10–15mg) produced higher average weight loss than semaglutide (Wegovy 2.4mg) — about 19.5–20.9% vs 14.9% at 68–72 weeks. That doesn't mean tirzepatide is right for everyone. Side-effect tolerance, cost, and access also matter.
Does the calculator include Foundayo (orforglipron)?
Yes. Foundayo was FDA-approved for chronic weight management in April 2026 and is included as a first-class option. It's the first FDA-approved once-daily oral GLP-1 receptor agonist for weight loss. The 17.2mg dose averaged 11.1% body-weight loss at 72 weeks in non-diabetic adults.
Is Foundayo cheaper than Wegovy or Zepbound?
It depends on the comparison. Foundayo's 12-month cash cost at 17.2mg via LillyDirect Self-Pay (with 45-day refill discipline) is about $3,338 — close to Wegovy 2.4mg ($3,888) and meaningfully less than Zepbound 15mg ($5,188). On cost-per-pound-lost, Foundayo lands around $152/lb because the average weight loss is also lower. Cheaper monthly doesn't always mean cheaper per pound.
Why does oral GLP-1 weight loss look lower than Zepbound on the calculator?
Because in head-to-head FDA-label trial averages, it is. Foundayo 17.2mg averaged 11.1% at 72 weeks. Zepbound 15mg averaged 20.9% at the same endpoint. That's not a calculator quirk — that's the trial data. If the trade-off you want is "no injections" or "lower monthly cost," Foundayo can still be the right call.
Does type 2 diabetes change GLP-1 weight loss results?
Yes. FDA-label trial tables show people with type 2 diabetes lose less weight on the same dose of the same drug — about 9.6% on Wegovy 2.4mg vs 14.9% without diabetes, about 12.8–14.7% on Zepbound 10–15mg vs 19.5–20.9% without diabetes, and about 5.1–9.6% on Foundayo vs 7.4–11.1% without.
Do I need a BMI of 30 to get a GLP-1 for weight loss?
Not always. Common screening criteria are BMI ≥30, or BMI ≥27 with a weight-related condition (such as high blood pressure, high cholesterol, sleep apnea, or type 2 diabetes). A licensed clinician decides whether treatment is appropriate based on your full health history.
Are compounded GLP-1s the same as Wegovy or Zepbound?
No. Compounded products are not FDA-approved as compounded and are not the same as FDA-approved generics. The FDA has issued warning letters to telehealth companies for marketing compounded GLP-1s as "generic Wegovy" or equivalent to FDA-approved drugs. Quality and dosing accuracy vary by pharmacy.
What's the cheapest way to get a GLP-1 for weight loss?
For eligible commercially insured patients, manufacturer savings cards can bring Wegovy or Zepbound as low as $25/month, subject to program rules. Without insurance, Wegovy via NovoCare is $349/month after a $199 introductory rate for the first two months; Zepbound via LillyDirect Self-Pay starts at $299/month; Foundayo starts at $149/month for the starting dose.
Will I gain the weight back if I stop?
In most cases, yes. Trial extension data showed people who stopped semaglutide regained roughly two-thirds of their prior weight loss within a year. Long-term weight maintenance on GLP-1s typically requires ongoing treatment.
Why doesn't this calculator do dose math (mg to mL or units)?
The FDA has reported dosing errors and adverse events from people miscalculating compounded GLP-1 doses. We don't combine weight-loss projections with dose math because the safety risk isn't worth it. Get your dosing instructions in writing from your prescriber.
Sources and verification
FDA prescribing information (primary sources)
- Wegovy (semaglutide) prescribing information
- Zepbound (tirzepatide) prescribing information
- Foundayo (orforglipron) prescribing information
FDA safety and regulatory
Manufacturer pricing (verified May 7, 2026)
Federal programs
Clinical trials referenced
STEP 1, STEP 2, STEP 5, STEP UP (semaglutide); OASIS-4 (oral semaglutide); SURMOUNT-1, SURMOUNT-2, SURMOUNT-4 (tirzepatide); SUSTAIN, SUSTAIN FORTE (semaglutide for type 2 diabetes); SURPASS (tirzepatide for type 2 diabetes); ATTAIN-1, ATTAIN-2 (orforglipron)
Important — please read
Educational estimates only. This calculator provides projections based on clinical trial averages and a logarithmic interpolation model. Individual results vary significantly based on adherence, dose escalation, lifestyle, side effects, medical history, and clinician-directed treatment changes. Approximately 9–17% of trial participants in no-T2D injection trials do not achieve 5% weight loss; oral and T2D lanes are higher.
Not medical advice. This tool does not replace consultation with a licensed healthcare provider. It does not diagnose eligibility, prescribe medication, or guarantee results. Do not start, stop, or change any medication based on calculator output.
FDA indication notes. Wegovy, Zepbound, and Foundayo are FDA-approved for chronic weight management. Ozempic and Mounjaro are FDA-approved for type 2 diabetes; use for weight loss is off-label. Compounded semaglutide and tirzepatide are prepared by licensed compounding pharmacies and are not FDA-approved as compounded products. Composition, dosing, and quality vary by pharmacy. Always verify the prescriber, pharmacy license, and current legal status before starting a compounded medication. Wegovy and Zepbound carry FDA boxed warnings related to thyroid C-cell tumors — review the full prescribing information before treatment.
Affiliate disclosure. Weight Loss Provider Guide may receive compensation from telehealth providers featured in our quiz and elsewhere on this site. This does not affect calculator output, which is anchored to independent clinical trial data. Our provider rankings are based on published methodology, not commission rates.
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