GLP-1 Weight Loss Calculator
Enter your weight and choose a medication to see a week-by-week projection built from that drug's own clinical-trial trajectory — Zepbound, Wegovy, Ozempic, and Saxenda each project differently because their trial results differ. Not a prediction; a realistic, evidence-based starting point.
The short answer
In the pivotal trials, mean weight loss was about 22.5% on Zepbound (tirzepatide, 72 wk), 14.9% on Wegovy (semaglutide 2.4 mg, 68 wk), and ~8% on Saxenda(liraglutide, 56 wk). This calculator applies each drug's real trajectory to your weight — averages with lifestyle support, not a personal guarantee.
Enter your current weight and pick a medication to see a projection based on that drug's published clinical-trial trajectory.
How the projection is calculated
Most "weight loss calculators" apply one generic percentage to everyone. This one uses the published mean weight-loss curve for the specific drug you pick: the percent of body weight participants lost at each point in that drug's pivotal trial, applied to the starting weight you enter. That is why Zepbound (SURMOUNT-1) projects more than Wegovy (STEP-1), which projects more than Ozempic (dosed lower, for diabetes).
What the numbers can — and can't — tell you
These are trial averages, measured in people who also followed a reduced-calorie diet and increased their activity. Around that average is a wide spread: many people lose less, some lose more, response depends on how high you titrate and how well you tolerate the dose, and weight commonly plateaus. The projection is a reasonable expectation-setter, not a forecast of your personal result, and it is not medical advice.
What actually drives your result
- Reaching an effective dose — most of the trial effect came at the higher maintenance doses, not the starter dose.
- Diet and activity — the trials paired the drug with lifestyle changes; the medication makes the calorie deficit easier to sustain, it doesn't replace it.
- Adherence and time — the curves span 56–72 weeks; most loss is in the first several months, then it slows.
- Individual biology and starting weight — higher starting weight often means more absolute pounds for the same percentage.
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Related
- Tirzepatide dosage chart — the dose that drives the Zepbound result.
- How long Zepbound takes to work — the timeline behind the curve.
- Calorie deficit calculator — the lifestyle side of the trial protocol.
Common questions about this medication
How does the GLP-1 weight loss calculator work?
It takes each medication’s published clinical-trial weight-loss trajectory — the mean percent of body weight lost at each point in the study — and applies it to the starting weight you enter. So Zepbound uses the SURMOUNT-1 curve (~22.5% at 72 weeks), Wegovy the STEP-1 curve (~14.9% at 68 weeks), and so on. The result is a drug-specific week-by-week projection rather than one generic number.
How much weight can you lose on GLP-1 medications?
In the pivotal trials, mean body-weight reduction was about 22.5% on tirzepatide (Zepbound, 72 weeks), 14.9% on semaglutide 2.4 mg (Wegovy, 68 weeks), and about 8% on liraglutide 3.0 mg (Saxenda, 56 weeks). Ozempic, dosed for diabetes, averaged less (~6%). These are averages with diet and activity support; individual results vary widely.
Is this calculator a prediction of my results?
No. It shows the trial-average trajectory applied to your weight, not a personalized prediction or guarantee. Real results depend on dose, how high you titrate, adherence, diet, activity, starting weight, and individual biology — many people lose less than the average, and weight often plateaus. Use it to set realistic expectations, then talk to a clinician.
Why does Zepbound project more weight loss than Wegovy or Ozempic?
Because their trials produced different mean results. Tirzepatide (Zepbound) is a dual GIP/GLP-1 agonist and reached ~22.5% mean loss in SURMOUNT-1; semaglutide 2.4 mg (Wegovy) reached ~14.9% in STEP-1; Ozempic is dosed lower for diabetes and averaged less. The calculator reflects those real differences instead of assuming every GLP-1 works the same.
When will I reach my goal weight?
If you enter a goal, the tool marks roughly where the trial-average trajectory crosses it. Most of the loss happens over the first several months and the curve flattens toward the trial endpoint (56–72 weeks depending on the drug). If your goal is below the trial-average endpoint, reaching it is possible but not typical — a clinician can help set a realistic target.
Trial figures reflect published results from SURMOUNT-1 (tirzepatide), STEP-1 (semaglutide), SCALE (liraglutide), and SUSTAIN (semaglutide, diabetes). Educational tool only — not medical advice, not a prediction, and not a substitute for a clinician. Reviewed 2026-07-15.