Tirzepatide Dosage Calculator
Calculate injection volumes for tirzepatide. Pre-filled for a 10mg vial with 2ml BAC water (5,000 mcg/ml).
Tirzepatide is a dual GIP and GLP-1 receptor agonist approved for type 2 diabetes (Mounjaro) and obesity (Zepbound). In trials, it produced greater weight loss than GLP-1-only agents — up to about 21% in SURMOUNT-1 versus 15% for semaglutide in STEP 1 (separate trials, not head-to-head).
For a 10mg tirzepatide vial: add 2ml of bacteriostatic water → concentration is exactly 5000 mcg/ml. For the standard 2.5mg (2500mcg) starting dose, inject 0.50ml (50 units) on a 100-unit syringe.
Dose Reference Table
Pre-calculated for a 10mg vial + 2ml BAC water = 5,000 mcg/ml concentration. Using a 100-unit (1ml) insulin syringe.
| Dose | Inject Volume (ml) | Syringe Units |
|---|---|---|
| 1250mcg (1.25mg) | 0.250 ml | 25 units |
| 2500mcg (2.5mg) | 0.500 ml | 50 units |
| 5000mcg (5mg) | 1.000 ml | 100 units |
| 7500mcg (7.5mg) | 1.500 ml | 150 units |
| 10000mcg (10mg) | 2.000 ml | 200 units |
About Tirzepatide
Tirzepatide is a dual GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptor agonist. It was developed and is FDA-approved under the brand name Mounjaro for type 2 diabetes and Zepbound for obesity. In research settings, it has attracted interest for its weight-reduction efficacy relative to GLP-1 monotherapy agents. Sources: SURMOUNT-1 (NEJM 2022), STEP 1 (NEJM 2021).
Research-grade tirzepatide is commonly supplied in 5mg, 10mg, and 15mg vials. The most practical reconstitution for a 10mg vial is 2ml of bacteriostatic water, yielding 5,000 mcg/ml. At this concentration, doses are expressed in milligrams for convenience: 2.5mg = 0.5ml = 50 units.
Tirzepatide has a half-life of approximately 5 days, supporting once-weekly subcutaneous administration. The FDA-labeled escalation schedule starts at 2.5mg/week and increases by 2.5mg every 4 weeks up to a maximum of 15mg/week, as tolerated (per prescribing information for Mounjaro, accessdata.fda.gov). Shown for reference only — this site does not recommend doses.
How this calculator works
Every result comes from the same three formulas used for any lyophilized peptide: concentration (mcg/ml) = vial mg × 1,000 ÷ BAC water ml; injection volume (ml) = desired dose mcg ÷ concentration; syringe units = injection volume ml × 100 on a U-100 syringe.
For the preset Tirzepatide setup on this page: a 10mg vial mixed with 2ml of bacteriostatic water gives a concentration of 5,000 mcg/ml. A 2,500mcg dose then needs 0.50ml, which is 50 units on a 100-unit insulin syringe.
The full methodology, with worked examples and the assumptions behind each formula, is on the methodology page.
Accuracy & limitations
The arithmetic itself is exact — the same inputs always produce the same output. Real-world accuracy depends on things outside the calculator: actual vial contents can vary slightly from the labeled amount within manufacturing tolerance, the BAC water volume should be measured carefully, and syringe readings are taken at the bottom edge of the plunger. Reconstituted peptides also degrade over time (the common guidance is to use within about 28 days refrigerated), which the math does not model. This tool does arithmetic only — it does not recommend doses, and it is not medical advice.
Last reviewed: September 2026 · Content, formulas and sources checked by Kanika