Tirzepatide 15 mg reconstituted with 4 mL
Concentration
3.75mg/mL
- Per insulin unit
- 37.5 mcg
- Solution in vial
- 400 u
- 2.5 mg draw
- 66.7 u
Math utility only — not medical advice. Not a recommended dose.
Units per dose at 3.75 mg/mL
Insulin syringes are graduated in hundredths of a millilitre, so units = mL × 100 on a U-100, U-50 or U-30 barrel alike.
| Dose | Volume | U-100 units | Fits | Doses per vial |
|---|---|---|---|---|
| 2.5 mg | 0.667 mL | 66.7 u | U-100 | 6 |
| 5 mg | 1.333 mL | 133.3 u | split draw | 3 |
| 7.5 mg | 2 mL | 200 u | split draw | 2 |
| 10 mg | 2.667 mL | 266.7 u | split draw | 1 |
| 12.5 mg | 3.333 mL | 333.3 u | split draw | 1 |
| 15 mg | 4 mL | 400 u | split draw | 1 |
Amber rows exceed 100 units — more than one full U-100 barrel. That dose needs a larger draw or a stronger mix (less water).
How this is calculated
1 · Concentration
15 mg ÷ 4 mL = 3.75 mg/mL
The peptide mass never changes — bacteriostatic water only sets how concentrated the solution is, and therefore how far the plunger travels.
2 · Volume for a 2.5 mg dose
2.5 mg ÷ 3.75 mg/mL = 0.667 mL
3 · Insulin units
0.667 mL × 100 = 66.7 units
Every unit on the barrel carries 37.5 mcg at this concentration, so misreading by one unit is a 37.5 mcg error.
See it on a real syringe
The interactive calculator draws this 3.75 mg/mL mix on a scaled U-100 barrel, shows when a draw lands exactly on a printed tick, and works backwards from a target dose to the water volume that makes it land cleanly.
Open the interactive calculator →Common questions
- How much bacteriostatic water for a 15 mg Tirzepatide vial?
- Adding 4 mL of bacteriostatic water to a 15 mg Tirzepatide vial yields 3.75 mg/mL — 37.5 mcg in every insulin unit. The reconstituted vial holds 400 units of solution in total.
- How many units is a 2.5 mg dose of Tirzepatide at 15 mg in 4 mL?
- 2.5 mg is 0.667 mL of this mix, which is 66.7 units on a U-100 insulin syringe (a U-100 barrel is enough).
- How many 2.5 mg doses does a 15 mg vial give?
- A 15 mg vial contains 6 full 2.5 mg doses. Using more or less bacteriostatic water changes the units you draw, never the number of doses in the vial.