How accurate is this tirzepatide weight-loss projection?

It is not a personal prediction. It applies the SURMOUNT-1 trial's mean (average) total-body-weight reduction at 72 weeks to your starting weight: about -15.0% at 5 mg, -19.5% at 10 mg, and -20.9% at 15 mg. Individual results in the trial ranged widely above and below those averages, and the trial paired the drug with dose titration and lifestyle support. Treat the number as a population average, not a guarantee.

Where do the percentages come from?

They are the mean percentage changes in body weight at week 72 from SURMOUNT-1, the phase 3 obesity trial of tirzepatide (Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022; PMID 35658024).

Why does the calculator show a week-by-week trajectory?

Weight loss on tirzepatide is steep early and tapers toward a plateau near 72 weeks. The milestone rows distribute each dose's 72-week mean across an illustrative early-fast, late-plateau curve so the shape is realistic. The intermediate weeks are an illustrative curve, not separate trial endpoints.

Does this tell me which dose to take?

No. The dose selector only looks up the trial's mean result at that maintenance dose. It is not a dose recommendation. Tirzepatide is prescription-only and is titrated under clinician supervision; talk to a licensed provider about what is appropriate for you.

ToolsProjection · SURMOUNT-1 data

Tirzepatide Weight-Loss Projection Calculator

Expected weight at ~72 weeks, from the SURMOUNT-1 trial averages

Enter your current weight and a maintenance dose, and this tool projects roughly where the average SURMOUNT-1 participant landed at 72 weeks — the phase 3 obesity trial of tirzepatide (the molecule in Zepbound and Mounjaro). It applies that trial’s mean total-body-weight reductions (5 mg ≈ −15%, 10 mg ≈ −19.5%, 15 mg ≈ −20.9%) to your number. It is a trial-average projection, not a personal prediction — the dose only looks up an average result.

Read before you use this

This is a projection based on clinical-trial group averages — not a promise, a personal prediction, or medical advice. SURMOUNT-1 reported mean weight loss; real individuals lost much more or much less, and the trial combined the drug with structured dose titration and lifestyle support. The tool does not recommend a dose, predict your individual response, or account for your health history, medications, side effects, or whether you can tolerate or stay on the drug. Tirzepatide is prescription-only; talk to a licensed clinician about whether it is right for you and what results are realistic.

Current weightlbEnter your starting weight in pounds. The projection applies a fixed percentage to this number.

Height (optional — adds a BMI estimate)

ftin

Leave blank to skip BMI. BMI is a population screening number, not a measure of health.

Maintenance dose

SURMOUNT-1 top maintenance dose: mean -20.9% of starting body weight at 72 weeks. This selects the trial’s mean result — it is not a recommendation to take this dose.

Enter your current weight to see a SURMOUNT-1-based projection.

How it is projected. The tool multiplies your starting weight by the SURMOUNT-1 mean total-body-weight reduction at 72 weeks for the dose you pick (5 mg ≈ −15.0%, 10 mg ≈ −19.5%, 15 mg ≈ −20.9%; Jastreboff et al., NEJM 2022, PMID 35658024), then subtracts that from your starting weight. The milestone rows distribute that same total across an illustrative early-fast / late-plateau curve. Worked example: 250 lb at 15 mg → −20.9% = 52 lb lost → ~198 lb. These are averages from a trial that paired the drug with structured titration and lifestyle support; individual outcomes vary widely.

Frequently asked

How accurate is this tirzepatide weight-loss projection?: It is not a personal prediction. It applies the SURMOUNT-1 trial's mean (average) total-body-weight reduction at 72 weeks to your starting weight: about -15.0% at 5 mg, -19.5% at 10 mg, and -20.9% at 15 mg. Individual results in the trial ranged widely above and below those averages, and the trial paired the drug with dose titration and lifestyle support. Treat the number as a population average, not a guarantee.
Where do the percentages come from?: They are the mean percentage changes in body weight at week 72 from SURMOUNT-1, the phase 3 obesity trial of tirzepatide (Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022; PMID 35658024).
Why does the calculator show a week-by-week trajectory?: Weight loss on tirzepatide is steep early and tapers toward a plateau near 72 weeks. The milestone rows distribute each dose's 72-week mean across an illustrative early-fast, late-plateau curve so the shape is realistic. The intermediate weeks are an illustrative curve, not separate trial endpoints.
Does this tell me which dose to take?: No. The dose selector only looks up the trial's mean result at that maintenance dose. It is not a dose recommendation. Tirzepatide is prescription-only and is titrated under clinician supervision; talk to a licensed provider about what is appropriate for you.

Understand the numbers before you set expectations

A projected number is the easy part. How the trials actually ran, how dosing is titrated, and what real results look like are what set honest expectations — read these next:

This calculator is informational and not medical advice. It performs simple arithmetic (projected weight = current weight × (1 − the SURMOUNT-1 mean reduction for the chosen dose)) and makes no judgment about what you will personally lose, what dose is right for you, or whether tirzepatide is appropriate. Clinical-trial averages are achieved under trial conditions and do not predict any one person’s outcome. Tirzepatide is available by prescription after clinician review.