--- title: "Weight-Loss Percentage Calculator | GLPMate" url: https://glpmate.me/tools/weight-loss-percentage-calculator language: en description: "Work out what percentage of your starting weight you've lost, with STEP 1 and SURMOUNT-1 trial averages shown only as context — never as a target." updated: 2026-10-14 --- Free tool · no signup # 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. **Your trend, without the maths** Log your weight in GLPMate and see the trend over weeks and months. [ Download on the **App Store** ](https://glpmate.go.link?adj_t=22klhq12&adj_campaign=tools-weight-loss-percentage-calculator&adj_redirect_android=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235&adj_redirect_macos=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235&adj_redirect_windows=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235) [ GET IT ON **Google Play** ](https://glpmate.go.link?adj_t=22klhq12&adj_campaign=tools-weight-loss-percentage-calculator&adj_redirect_ios=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate&adj_redirect_macos=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate&adj_redirect_windows=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate) Quick answer 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. **Context, not a target:** trial averages come from large groups after 68–72 weeks on a full dose, alongside diet and activity support. Your pace depends on your dose, how long you've been taking it, your starting point and much more — comparing week 8 with a week-72 average tells you very little. [See a trial-average projection →](/tools/weight-loss-projection) ## 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. ## Related free tools [ **Weight-loss projection** What the trial averages look like on your scale. Open tool → ](/tools/weight-loss-projection)[ **Weight tracker** Your trend over weeks and months in the app. Learn more → ](/glp-1-weight-tracker)[ **BMI calculator** Your BMI category and healthy-weight range. Open tool → ](/tools/bmi-calculator) 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 1. [STEP 1 trial (semaglutide 2.4 mg, 68 weeks)](https://doi.org/10.1056/NEJMoa2032183) — mean body-weight change −14.9% vs −2.4% with placebo 2. [SURMOUNT-1 trial (tirzepatide 5, 10 and 15 mg, 72 weeks)](https://doi.org/10.1056/NEJMoa2206038) — mean body-weight change −15.0%, −19.5% and −20.9% vs −3.1% with placebo Last updated: 2026-10-14 FAQ ## 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. [ Download on the **App Store** ](https://glpmate.go.link?adj_t=22klhq12&adj_campaign=tools-weight-loss-percentage-calculator&adj_redirect_android=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235&adj_redirect_macos=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235&adj_redirect_windows=https%3A%2F%2Fapps.apple.com%2Fapp%2Fid6788548235) [ GET IT ON **Google Play** ](https://glpmate.go.link?adj_t=22klhq12&adj_campaign=tools-weight-loss-percentage-calculator&adj_redirect_ios=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate&adj_redirect_macos=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate&adj_redirect_windows=https%3A%2F%2Fplay.google.com%2Fstore%2Fapps%2Fdetails%3Fid%3Dapp.eleutheromania.glpmate)