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Weight-loss percentage calculator
Enter your starting and current weight to see how much you've lost as a percentage — the way clinicians and clinical trials measure progress.
Log your weight in GLPMate and see the trend over weeks and months.
Percentage lost = (starting weight − current weight) ÷ starting weight × 100. For context only: the average loss at the end of the pivotal trials was 14.9% with semaglutide 2.4 mg after 68 weeks (STEP 1) and 15.0–20.9% with tirzepatide 5–15 mg after 72 weeks (SURMOUNT-1). Individual results vary widely, and these averages are not a target.
How it's calculated
Percentage lost = (starting − current) ÷ starting × 100. A percentage, rather than kilograms or pounds, makes progress comparable between people of different sizes — which is why clinical trials report it.
| Trial | Medication | Average change | Placebo | Duration |
|---|---|---|---|---|
| STEP 1 | semaglutide 2.4 mg | −14.9% | −2.4% | 68 weeks |
| SURMOUNT-1 | tirzepatide 5 mg | −15.0% | −3.1% | 72 weeks |
| SURMOUNT-1 | tirzepatide 10 mg | −19.5% | −3.1% | 72 weeks |
| SURMOUNT-1 | tirzepatide 15 mg | −20.9% | −3.1% | 72 weeks |
Average change in body weight at the end of each trial, in adults with obesity, or overweight with a weight-related condition, without diabetes, alongside lifestyle support.
Plateaus are normal
Weight loss on a GLP-1 usually slows over time and often levels off. Day-to-day changes are noisy — water, salt and digestion all move the scale — so a trend over several weeks says more than any single weigh-in.
This calculator is for general education only. It is not medical advice, and trial averages are not a prediction or a goal for you. Talk to your clinician about what progress means in your situation.
Sources
- STEP 1 trial (semaglutide 2.4 mg, 68 weeks) — mean body-weight change −14.9% vs −2.4% with placebo
- SURMOUNT-1 trial (tirzepatide 5, 10 and 15 mg, 72 weeks) — mean body-weight change −15.0%, −19.5% and −20.9% vs −3.1% with placebo
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Weight-loss questions
How do I calculate my weight-loss percentage?
Subtract your current weight from your starting weight, divide by your starting weight and multiply by 100. For example, going from 100 kg to 92 kg is an 8% loss.
What is the average weight loss on semaglutide or tirzepatide?
In STEP 1, adults on semaglutide 2.4 mg lost an average of 14.9% of their body weight over 68 weeks (2.4% with placebo). In SURMOUNT-1, tirzepatide averaged 15.0%, 19.5% and 20.9% at 5, 10 and 15 mg over 72 weeks (3.1% with placebo). Individual results ranged widely.
Why is my percentage different from the trial averages?
Trials report averages after 68–72 weeks at a full dose, with lifestyle support. Your dose, time on treatment, starting weight, other health conditions and medicines all play a part, and many people lose more or less than the average.
How often should I weigh myself?
Some people prefer daily weigh-ins for a smoother average, others weekly. Either way, weigh at the same time of day and look at the trend over several weeks rather than single days.
Watch the trend, not the day.
Weight trend, doses and side effects together in GLPMate. iOS & Android.