What Is the GLP-1 Weight Loss Calculator?
The GLP-1 Weight Loss Calculator is a free online tool designed for users who need quick, accurate calculations in the practical calculation space. By entering your current weight, height, medication, you get instant results including projected weight, total loss, body weight lost. No formulas to memorize, no spreadsheets to build — just enter your numbers and get the answer in seconds. Whether you're a beginner or experienced professional, this calculator saves you time and eliminates guesswork.
Why This Calculation Matters
Getting projected weight right can make the difference between success and costly mistakes. In practical calculation, small errors compound quickly. Manual calculations are error-prone and time-consuming, especially under pressure. This calculator applies proven formulas used by users worldwide, giving you confidence that your numbers are correct. Use it to get accurate results with precision and avoid common pitfalls that trip up beginners.
When Should You Use This Calculator?
This tool is most useful when you know your current weight and need to find the right projected weight. It's also great for quick estimates before committing to a decision, and to double-check manual calculations or professional quotes, and when comparing different scenarios side by side. Bookmark this page and come back whenever you need a fast, reliable answer — the calculator is always free and requires no signup.
GLP-1 Weight Loss Calculator
Average Weight Loss by Medication Over 68 Weeks
Projected weight loss for a 220 lb starting weight based on clinical trial averages
| Week | Wegovy | Ozempic | Mounjaro/Zepbound |
|---|---|---|---|
| Week 4 | 215 lbs (-2.3%) | 217 lbs (-1.4%) | 214 lbs (-2.7%) |
| Week 12 | 207 lbs (-5.9%) | 211 lbs (-4.1%) | 204 lbs (-7.3%) |
| Week 24 | 197 lbs (-10.5%) | 204 lbs (-7.3%) | 190 lbs (-13.6%) |
| Week 36 | 191 lbs (-13.2%) | 200 lbs (-9.1%) | 183 lbs (-16.8%) |
| Week 52 | 188 lbs (-14.5%) | 197 lbs (-10.5%) | 177 lbs (-19.5%) |
| Week 68 | 187 lbs (-15.0%) | 196 lbs (-10.9%) | 171 lbs (-22.3%) |
How to Use This Calculator
- Enter Your Current Weight (lbs): Start by entering your current weight — this is the primary input for the calculation.
- Fill In Additional Details: Complete the remaining fields: height, medication, goal weight, projection timeline. Each value refines the calculation for greater accuracy.
- Click Calculate: Hit the Calculate button to run the numbers. Results appear instantly below.
- Review Your Results: Check your projected weight, total loss, body weight lost. Use these figures to inform your next decision or compare against alternative scenarios.
How It Works
This calculator projects weight loss over time using average results from major GLP-1 receptor agonist clinical trials. It models the typical weight loss curve — rapid loss in months 1-6, gradual slowing through month 12, and plateau around months 15-18.
The basic rule:
- Wegovy (semaglutide 2.4mg): ~15% average body weight loss over 68 weeks (STEP 1 trial)
- Ozempic (semaglutide 1mg): ~10-12% body weight loss over 68 weeks (SUSTAIN trials, lower dose than Wegovy)
- Mounjaro/Zepbound (tirzepatide 15mg): ~22.5% body weight loss over 72 weeks (SURMOUNT-1 trial)
- Weight loss follows a logarithmic curve — fastest in early months, plateauing as the body adapts
These projections reflect population averages from clinical trials. About one-third of patients exceed the average, one-third hit the average, and one-third fall below. Diet, exercise, dose titration, and genetics all affect individual results. Discuss expectations with your prescriber.
Tips & Considerations
- Double-check your current weight before calculating — even small input errors can significantly change your results.
- Run the calculator with different values to compare scenarios and find the optimal approach for your situation.
- Pay attention to both projected weight and total loss — they work together to give you the full picture.
- Bookmark this page for quick access next time you need to get accurate results.
- If you're unsure about your projection timeline, start with a conservative estimate and adjust from there.
Frequently Asked Questions
How much weight can I lose on Ozempic vs Wegovy?
Wegovy typically produces more weight loss than Ozempic because the maintenance dose is higher (2.4mg vs 1mg semaglutide). Clinical trials show about 15% body weight loss with Wegovy vs 10-12% with Ozempic over 68 weeks. Both are semaglutide — Wegovy is specifically FDA-approved for weight management at the higher dose.
Is Mounjaro or Zepbound more effective than Wegovy?
Clinical trial data suggests tirzepatide (Mounjaro/Zepbound) produces greater weight loss than semaglutide (Wegovy) — about 22.5% vs 15% body weight loss. The SURMOUNT-4 trial showed up to 26% loss in some cohorts. However, head-to-head trials are limited, and individual responses vary significantly.
When does weight loss plateau on GLP-1 medications?
Most patients see the fastest weight loss during months 2-6 after reaching the maintenance dose. Weight loss continues but slows through months 6-12, and typically plateaus around months 15-18. Some patients continue to lose small amounts beyond 18 months, especially with diet and exercise optimization.
What happens if I stop taking a GLP-1 medication?
The STEP 1 extension trial showed that patients regained about two-thirds of their lost weight within one year of stopping semaglutide. This is a key consideration — most experts recommend planning for long-term use. Lifestyle changes made during treatment can help reduce (but not eliminate) rebound.
How accurate is this calculator?
This calculator uses population averages from published clinical trials. About 33% of patients lose more than the average, 33% hit roughly the average, and 33% lose less. Factors including genetics, diet, exercise, starting BMI, dose achieved, and medication adherence all significantly affect individual outcomes.
What are common side effects of GLP-1 medications?
The most common side effects are gastrointestinal — nausea (30-45% of patients), vomiting, diarrhea, and constipation. These are usually worst during dose escalation and improve over time. Serious but rare risks include pancreatitis, gallbladder disease, and thyroid C-cell tumors (seen in animal studies). Always discuss risks with your doctor.