Mounjaro Weight Loss Calculator

Mounjaro is available in six strengths: 2.5, 5, 7.5, 10, 12.5 and 15 mg. SURMOUNT-1 only randomised participants to three maintenance doses, 5 mg, 10 mg and 15 mg, so those are the only doses with a published weight-loss result. We have deliberately not invented curves for 7.5 mg and 12.5 mg.

If you are on one of those strengths, read between the two curves either side of it. Someone maintaining on 12.5 mg sits somewhere between the 10 mg and 15 mg lines, which at the 72-week endpoint means somewhere between 19.5% and 20.9%. That is a wide enough band to be honest about, and narrower than the spread between individuals on any single dose.

The 2.5 mg strength is a starting dose rather than a maintenance dose. It is there to let your body adjust, and it is not expected to deliver the full effect on its own.

Nobody starts on a maintenance dose. Tirzepatide begins at 2.5 mg once weekly for four weeks, moves to 5 mg, and then rises in 2.5 mg steps no sooner than every four weeks. The earliest anyone reaches 15 mg is around week 20, so most of the first four to five months are spent climbing rather than sitting at the dose the curve is named after.

That is why the trial curves are steepest through months 3 to 9 rather than in month 1. At week 12 the estimated 15 mg trajectory is only about 9.0%, well under half of where it finishes. If you are eight weeks in and comparing yourself to a headline number from week 72, you are comparing two different points on the same line.

Move the week slider on the calculator to where you actually are. What you want is your own trend against the curve at the same week, not against the endpoint.

An average hides an enormous range. On 15 mg at 72 weeks, 90.9% of participants lost at least 5%, 83.5% of participants lost at least 10%, 70.6% of participants lost at least 15%, and 56.7% of participants lost at least 20%. More than half cleared 20%, and roughly one in ten did not reach 5%, on the same dose in the same trial.

A slow start is a weak signal. In a SURMOUNT-1 follow-up analysis, 18% of participants had lost less than 5% at week 12, yet 90% of that group still reached at least 5% by week 72. True non-response by the end of the trial was under 2%.

Which is the practical case for keeping your own record rather than eyeballing it. Weekly weigh-ins under the same conditions, logged next to your doses and side effects, tell you and your prescriber far more than any single comparison to a trial average. GlucoPal is the free iPhone app built for that record, and it works in kilograms or stone as well as pounds.

It is a reference point, not a forecast. The published endpoints at week 72 and the responder percentages above are verified trial numbers. Everything between those points is modelled: SURMOUNT-1 publishes its week-by-week trajectory only as a figure, never as a numeric table. We draw a standard saturating weight-loss curve through the verified anchors, hit the published endpoint exactly, and label every intermediate week as estimated.

We also use the conservative regulator-signed estimand throughout rather than the higher efficacy numbers quoted in press coverage, which is why you will see 20.9% here for 15 mg rather than the ~22.5% figure you may have read elsewhere.

Finally, the trial population may not be yours: BMI 30 or above, or 27 and above with a weight-related condition, no diabetes, and a structured diet and activity programme running alongside the medication. The numbers reflect medication plus lifestyle change, not medication on its own. They are educational, not medical advice.