Tirzepatide dosage calculator
You are trying to work out how much to draw or when to step up.
Reference and calculator, not medical advice. Dosing figures below are transcribed from FDA-approved prescribing information and link back to it. Last reviewed August 2026.
The calculator is below. Enter your dose and the concentration printed on your vial; it returns the mark on a U-100 syringe, the volume in millilitres, and the formula it used so you can check it.
mg → syringe units converter
U-100 syringe. Formula: (dose ÷ concentration) × 100.
Check the concentration printed on the vial you are actually holding. The same dose in milligrams is a completely different mark on the syringe at a different concentration. If the number here does not match what your prescriber told you, trust your prescriber.
What a calculator can do here is arithmetic. What it cannot do is tell you which dose you should be on — that is set by your prescriber, and the labelled schedule below is the reference they work from, not a menu to pick from.
Zepbound titration schedule
Tirzepatide · once weekly · subcutaneous injection · as published in the prescribing information
| Step | Dose | Notes |
|---|---|---|
| Weeks 1–4 | 2.5 mg | Starting dose — not intended for weight loss effect |
| Weeks 5–8 | 5 mg | — |
| Weeks 9–12 | 7.5 mg | — |
| Weeks 13–16 | 10 mg | — |
| Weeks 17–20 | 12.5 mg | — |
| Week 21+ | 15 mg | Maximum dose |
This is the labelled default. Holding at a step longer than shown is common practice and is a decision for your prescriber. Transcribed from the Zepbound prescribing information (label revised 6 May 2026); checked against that label on 7 August 2026.
Zepbound dose → units reference
U-100 syringe units for each labelled dose, at the concentrations commonly supplied.
| Dose | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|
| 2.5 mg | 50.0 u | 25.0 u | 12.5 u |
| 5 mg | 100.0 u | 50.0 u | 25.0 u |
| 7.5 mg | 150.0 u | 75.0 u | 37.5 u |
| 10 mg | 200.0 u | 100.0 u | 50.0 u |
| 12.5 mg | 250.0 u | 125.0 u | 62.5 u |
| 15 mg | 300.0 u | 150.0 u | 75.0 u |
Only use the column matching the concentration printed on your vial.
Common questions
- Why does the calculator ask for concentration?
- Because without it the question has no answer. Milligrams measure drug; syringe units measure volume. Converting between them requires knowing how much drug is in each millilitre, which is the concentration.
- Can it work out my dose from my weight?
- No, and no calculator should. Tirzepatide is dosed on a fixed stepped schedule, not by body weight, and where you sit on that schedule is a clinical decision.
- Does it save anything I enter?
- Nothing. The arithmetic runs entirely in your browser; the site is a static export with no server to send it to.
Common questions
- What is the starting dose of Zepbound?
- The prescribing information lists 2.5 mg once weekly as the starting dose, held for the first four weeks before any increase.
- What is the maximum labelled dose of Zepbound?
- 15 mg once weekly, reached through the stepped schedule shown above.
- How many units is 5 mg at 20 mg/mL?
- 25.0 units on a U-100 syringe. The arithmetic is (dose ÷ concentration) × 100, and it only holds if the concentration on your vial matches.
Sources and last review
Every dosing figure on this page is transcribed from an FDA-approved label and links back to it. Conversions are arithmetic you can repeat by hand. Nothing here is reviewed by a clinician, and this site does not employ one — which is exactly why what I do publish stays traceable to its source.
- Zepbound (Tirzepatide) prescribing information — Eli Lilly, label revised 6 May 2026, checked 7 August 2026
Transcribed from the labels above and checked by me — Gavin, who builds this site, takes a GLP-1, and is not a clinician. Last reviewed August 2026. Found an error? [email protected] — I treat corrections as bugs. How this site is built and funded.
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