How many units is 12.5 mg of tirzepatide?

It depends on exactly one thing: the concentration printed on your vial. Here it is at the 4 strengths compounded tirzepatide usually comes in, and drawn on the barrel.

At 5 mg/mL, 12.5 mg is 250 units — more than one syringe holds. At 10 mg/mL, 12.5 mg is 125 units — more than one syringe holds. At 20 mg/mL, 12.5 mg is 62.5 units (0.625 mL). At 40 mg/mL, 12.5 mg is 31.25 units (0.313 mL).

12.5 mg of tirzepatide, by vial concentration. U-100 insulin syringe.
Vial says	Which is	mL	Units	Syringe
5 mg / 1 mL 10 mg / 2 mL 15 mg / 3 mL	5 mg/mL	2.5	250 ✗	does not fit in one syringe
10 mg / 1 mL 20 mg / 2 mL 30 mg / 3 mL 50 mg / 5 mL	10 mg/mL	1.25	125 ✗	does not fit in one syringe
20 mg / 1 mL 40 mg / 2 mL 60 mg / 3 mL	20 mg/mL	0.625	62.5	100-unit
40 mg / 1 mL 80 mg / 2 mL	40 mg/mL	0.313	31.25	50-unit

What that looks like on the barrel

250 units — more than one syringe holds. 2.5 mL: that's two draws, or a stronger vial.

5 mg/mL → 250 units

125 units — more than one syringe holds. 1.25 mL: that's two draws, or a stronger vial.

10 mg/mL → 125 units

20 mg/mL → 62.5 units on a 100-unit syringe

40 mg/mL → 31.25 units on a 50-unit syringe

About this dose

Weeks 17–20. Rarely a destination; usually a step between 10 and 15 for people who didn't tolerate the full jump. At 20 mg/mL it's 62.5 units, between the 62 and 64 marks on a 100-unit barrel — the 50-unit syringe is no longer an option. At 40 mg/mL, 31.25 units on a 50-unit syringe reads cleanly.

Check it yourself

The whole sum is units = dose ÷ concentration × 100. For this dose at 20 mg/mL: 12.5 ÷ 20 × 100 = 62.5. If your vial isn't marked in mg/mL, the concentration is the vial's total milligrams divided by the water that went in — a 40 mg vial with 2 mL of water is 20 mg/mL.

Not one of those concentrations?

Tirzepatide vial → unitsU-100 syringe

Vial strength mg

Water you added mL

Your dose mg

Syringe

—

Fill in all three boxes.

Common setups:

← 10 mg 15 mg →

Other doses: 2.5 mg · 5 mg · 7.5 mg · 10 mg · 15 mg. The whole ladder, with every dose at every strength: the tirzepatide chart. Going the other way — you drew a number of units and want the milligrams — is here. And if the vial isn't tirzepatide at all, mg to units works for anything.