Quick math example
A 10 mg vial mixed with 2 mL gives 5 mg/mL. A 2.5 mg dose is 0.5 mL, which equals 50 units on a U-100 syringe.
Tirzepatide 5 mg vial reference
U100 units to draw for each common Tirzepatide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 2.5 mg | 5 mg | 7.5 mg | 10 mg | 12.5 mg |
|---|---|---|---|---|---|---|
| 5 mg | 2.5 mg/mL | 100 u(1 mL) | 200 u(2 mL) | 300 u(3 mL) | 400 u(4 mL) | 500 u(5 mL) |
Educational reference only — not a dose recommendation. Units assume a U100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
5 mg tirzepatide vial examples
A 5 mg vial in 2 mL gives 2.5 mg/mL (2,500 mcg/mL). A 2.5 mg dose is a full 1.0 mL — 100 units, the whole length of a 1 mL U-100 syringe.
To shrink that draw, use less water: 5 mg in 1 mL gives 5 mg/mL, so a 2.5 mg dose drops to 0.5 mL (50 units). A starter dose of 1.25 mg at 2.5 mg/mL is 0.5 mL (50 units).
- 5 mg / 2 mL = 2.5 mg/mL → 2.5 mg = 1.0 mL = 100 units
- 5 mg / 1 mL = 5 mg/mL → 2.5 mg = 0.5 mL = 50 units
- A 5 mg vial holds about two 2.5 mg doses
The 5 mg vial as a titration starter
The 5 mg vial fits the first weeks of a tirzepatide titration, where weekly doses are small. It covers only a couple of full 2.5 mg doses, so it is best when you are still stepping up and changing the dose often, rather than settled on maintenance.
Because a 2.5 mg dose can fill a whole syringe at 2.5 mg/mL, pick your water volume deliberately — most people reconstitute a 5 mg vial in 1 mL to keep the draw at 50 units or below.
- Best for early titration (2.5 mg/week and below)
- Reconstitute in 1 mL to keep a 2.5 mg dose at 50 units
- Swap to a larger vial once you reach maintenance dosing
How the tirzepatide calculation works
Tirzepatide doses are often discussed in milligrams, while many vials and syringes require you to think in mg, mcg, mL, and units at the same time.
The calculator normalizes everything into concentration first, then returns a draw volume and matching syringe-unit result.
- 10 mg equals 10,000 mcg
- 10,000 mcg / 2 mL = 5,000 mcg per mL
- 2,500 mcg / 5,000 mcg per mL = 0.5 mL
Tirzepatide 10 mg vial with 2 mL example
A 10 mg tirzepatide vial mixed with 2 mL gives 5 mg/mL, or 5,000 mcg/mL.
A 2.5 mg target dose is 2,500 mcg. At 5 mg/mL, that is 0.5 mL, which equals 50 units on a U-100 syringe.
- 10 mg / 2 mL = 5 mg/mL
- 2.5 mg = 2,500 mcg
- 2,500 mcg / 5,000 mcg per mL = 0.5 mL = 50 U-100 units
Tirzepatide 15 mg vial with 3 mL example
A 15 mg tirzepatide vial mixed with 3 mL also gives 5 mg/mL, or 5,000 mcg/mL.
Because the concentration is the same as the 10 mg with 2 mL example, a 2.5 mg dose is still 0.5 mL, or 50 U-100 units.
- 15 mg / 3 mL = 5 mg/mL
- 2.5 mg / 5 mg per mL = 0.5 mL
- 0.5 mL x 100 = 50 U-100 units
How much BAC water for tirzepatide?
Bacteriostatic water volume sets your concentration, so it directly changes the syringe units you draw. There is no single correct amount — choose a volume that puts your target dose at an easy-to-read number of units on a U-100 syringe.
For a 10 mg vial: 1 mL gives 10 mg/mL (a 2.5 mg dose = 0.25 mL = 25 units), 2 mL gives 5 mg/mL (2.5 mg = 0.5 mL = 50 units), and 3 mL gives about 3.33 mg/mL (2.5 mg = 0.75 mL = 75 units).
- More BAC water = lower concentration = more units for the same dose
- 10 mg / 1 mL = 10 mg/mL; 10 mg / 2 mL = 5 mg/mL; 10 mg / 3 mL = 3.33 mg/mL
- Aim for a draw that lands on clear unit markings to reduce dosing error
When to re-check the math
Recalculate when you change vial size, BAC water volume, dose, syringe type, or syringe capacity. Saving the setup in PepSync helps avoid re-entering the same details each week.