Free Tools
GLP-1 calculators
By GLP AI / Editorial. Education only, not medical advice.
What is a GLP-1 calculator?
"GLP-1 calculator" is not one tool. People use the name for several different calculations, and each one answers a different question: how much medication is in your body today, how much weight people lost in the trials, how much protein to eat, where to inject next, or how two medications compare.
The calculators below are free and work for Ozempic, Wegovy, Mounjaro, Zepbound and compounded semaglutide or tirzepatide. They are educational estimates. None of them can set or change a dose; that decision belongs to your prescriber.
- GLP-1 medication level calculator. Estimates how much semaglutide or tirzepatide is in your body on each day of the dose week, from your medication, dose, injection date and weight. Use it to see when a dose peaks and how long it stays in your system.
- GLP-1 weight loss calculator. Looks up the average weight change published for Zepbound, Wegovy, Ozempic or Mounjaro in its own clinical trial, by dose, and for the obesity trials applies it to your starting weight. It reports a trial average; it is not a prediction.
- GLP-1 protein calculator. Gives a daily and per-meal protein target in grams, from your weight, height, age, sex, activity level, goal and strength training.
- GLP-1 injection site tracker. Builds a rotation schedule across the abdomen, thighs, arms, flanks and buttocks, from your medication and the sites you are willing to use.
- Compare GLP-1 medications. Puts Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda and Rybelsus side by side in one table; you choose which medications to show.
Calculators by medication
Protein Calculator
Calculate your optimal daily protein intake to preserve muscle mass while losing weight on Ozempic, Wegovy, Mounjaro, or Zepbound.
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Injection Site Tracker
Prevent lipodystrophy by rotating injection sites. Track your weekly injections with a personalized schedule for Ozempic, Mounjaro, Wegovy, and Zepbound.
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GLP-1 Medication Level Calculator
Visualize when your Ozempic, Mounjaro, Wegovy, or Zepbound peaks. Understand your medication levels, plan meals around side effects, and optimize your GLP-1 journey. Free pharmacokinetic calculator.
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Mounjaro Half-Life Calculator
Visualize when your Mounjaro (tirzepatide) peaks, track your medication levels over time, and optimize your injection schedule. Tirzepatide has a half-life of approximately 5 days.
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Ozempic Half-Life Calculator
Visualize when your Ozempic (semaglutide) peaks, track your medication levels over time, and optimize your injection schedule. Semaglutide has a half-life of approximately 7 days.
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Zepbound Half-Life Calculator
Visualize when your Zepbound (tirzepatide) peaks, track your medication levels over time, and optimize your injection schedule. Tirzepatide has a half-life of approximately 5 days.
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Wegovy Half-Life Calculator
Visualize when your Wegovy (semaglutide) peaks, track your medication levels over time, and optimize your injection schedule. Semaglutide has a half-life of approximately 7 days.
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Semaglutide Half-Life Calculator
Visualize when semaglutide peaks and how long it stays in your system. Works for Ozempic, Wegovy, Rybelsus, and compounded semaglutide doses.
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Tirzepatide Half-Life Calculator
Visualize when tirzepatide peaks and how long it stays in your system. Works for Mounjaro, Zepbound, and compounded tirzepatide doses.
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GLP-1 Weight Loss Calculator
See the average weight change published for Zepbound, Wegovy, Ozempic or Mounjaro in its own clinical trial, by dose. A lookup of trial results, not a prediction.
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Compare GLP-1 Medications
Put Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda and Rybelsus side by side in one table, and choose which medications to show.
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Why Use Specialized GLP-1 Tools?
Managing weight loss on medications like Ozempic, Wegovy, Mounjaro, or Zepbound requires more than just a scale. Appetite is lower on these medications, so protein is easy to under-eat. Our Protein Calculator sets a daily and per-meal target from your weight, height, age, activity level and goal.
Understanding the half-life of your medication helps prevent side effects and optimize timing. Our Medication Level Calculators help you visualize when medication levels peak in your system, allowing you to plan meals and activities around peak effectiveness and potential side effects.
Proper injection site rotation prevents lipodystrophy—a condition where repeated injections in the same spot cause fatty lumps or depressions that can reduce medication absorption. Our Injection Site Tracker provides a simple, personalized rotation schedule to keep your injections effective and your skin healthy.
All our tools are free to use. The medication level calculators use the half-lives published in FDA prescribing information. They are educational estimates; decisions about your dose belong to your prescriber.
GLP-1 calculator questions
What is a GLP-1 calculator?
A GLP-1 calculator is any tool that turns the details of your GLP-1 treatment into a number you can plan around. The common ones estimate your medication level across the dose week (often called a half-life calculator), set a daily protein target, or plan an injection-site rotation. They are educational tools, not medical devices.
Is there a calculator that shows how long a GLP-1 stays in your system?
Yes. The GLP-1 medication level calculator and the per-drug half-life calculators plot the estimated amount of medication in your body after each dose. Semaglutide (Ozempic, Wegovy) has a half-life of about 7 days, so it takes roughly 35 days to clear almost completely after the last dose. Tirzepatide (Mounjaro, Zepbound) has a half-life of about 5 days and takes roughly 25 days.
Which calculator shows when my dose peaks?
The GLP-1 medication level calculator, or the half-life calculator for your medication. Semaglutide typically reaches its peak 24 to 72 hours after an injection and tirzepatide 8 to 72 hours after, which is why most people feel the strongest effects one to three days after their shot. The chart marks the peak for the dose and date you enter.
Are these GLP-1 calculators free?
Yes. Every calculator on this page is free, and each one shows its result on the page without an account.
Do the calculators work for compounded semaglutide or tirzepatide?
The half-life calculators model the molecule, not the brand, so you can choose semaglutide or tirzepatide and enter your own dose. Compounded products are not FDA-approved and their formulation can differ from the branded pens, so treat the curve as an estimate.
How accurate are the numbers?
The medication level calculators use a one-compartment pharmacokinetic model with the half-lives published in FDA prescribing information. That describes an average person. Your own levels depend on your metabolism, kidney and liver function, body composition and other medications, so the results are estimates for learning and planning, not measurements.
Can a GLP-1 calculator tell me what dose to take?
No. None of these calculators recommends, sets or adjusts a dose. Your dose and titration schedule are decided by your prescriber, following the prescribing information for your medication. Bring the chart to your appointment if it helps the conversation.