DoseRoutine

Tirzepatide Reconstitution Calculator

Compounded tirzepatide comes as powder in a wide range of vial sizes, and the same 5 mg dose can be anywhere from 10 to 100 units depending on how you mixed it. Enter your vial and BAC water volume for the exact draw.

This is a unit converter. It converts an amount you already have into volume and syringe units. It does not tell you what to take, and it is educational only — not medical advice. Confirm every amount with your clinician and your product label.

Common setups

Vial size (mg)

Total compound in the vial.

BAC water added (mL)

Volume of bacteriostatic water you reconstitute with.

Target dose

Per-injection dose you want to draw.

Syringe type

U-100 = 100 units per mL (standard). U-40 = 40 units per mL.

Draw

25.0 units

on a U-100 insulin syringe (0.250 mL)

Concentration

10.00 mg/mL

Per dose

2.50 mg

Doses / vial

~12

Tirzepatide concentration reference (mg/mL)

What each vial size becomes at common bacteriostatic water volumes.

Vial	+ 1 mL	+ 2 mL	+ 3 mL	+ 5 mL
10 mg	10.00 mg/mL	5.00 mg/mL	3.33 mg/mL	2.00 mg/mL
15 mg	15.00 mg/mL	7.50 mg/mL	5.00 mg/mL	3.00 mg/mL
20 mg	20.00 mg/mL	10.00 mg/mL	6.67 mg/mL	4.00 mg/mL
30 mg	30.00 mg/mL	15.00 mg/mL	10.00 mg/mL	6.00 mg/mL
40 mg	40.00 mg/mL	20.00 mg/mL	13.33 mg/mL	8.00 mg/mL
60 mg	60.00 mg/mL	30.00 mg/mL	20.00 mg/mL	12.00 mg/mL

Tirzepatide dosing at a glance

Phase	Dose	Frequency	Notes
Weeks 1–4	2.5 mg	Once weekly	Starting dose — not intended for weight loss on its own.
Weeks 5–8	5 mg	Once weekly	First maintenance dose.
Weeks 9+	7.5–15 mg	Once weekly	Escalate in 2.5 mg steps, minimum 4 weeks apart.
Maximum	15 mg	Once weekly	Highest labelled dose for Mounjaro and Zepbound.

Reference ranges reported in the literature and in common practice — not a prescription, and not personalised advice.

What trips people up

Mixing 1 mL of BAC water per 10 mg of tirzepatide gives a tidy 10 mg/mL: 2.5 mg = 25 units, 5 mg = 50 units.
Branded pens (Mounjaro, Zepbound) come pre-filled — this calculator is for compounded or research powder vials only.
Never escalate faster than every 4 weeks. Most severe GI side effects come from rushing titration.
Tirzepatide is a GLP-1/GIP dual agonist and slows gastric emptying, which can change how quickly oral medications are absorbed.

How the maths works

Concentration (mg/mL) = vial mg ÷ bacteriostatic water mL.
Volume per dose (mL) = dose mg ÷ concentration.
Syringe units = volume × 100 on a U-100 syringe, or × 40 on a U-40 syringe.
Doses per vial = vial mg ÷ dose mg. Water volume never changes this number.

Tirzepatide calculator FAQ

How much BAC water do I add to a 30 mg tirzepatide vial?

3 mL is the most common choice, giving 10 mg/mL. On that concentration a 2.5 mg dose is 25 units, 5 mg is 50 units, 7.5 mg is 75 units and 10 mg is 100 units — a full U-100 syringe.

How many units is 5 mg of tirzepatide?

At 10 mg/mL it is 0.5 mL = 50 units on a U-100 syringe. At 20 mg/mL (30 mg + 1.5 mL) the same dose is 25 units. Concentration is the only thing that decides this.

How long does reconstituted tirzepatide last?

Refrigerated and mixed with bacteriostatic water, it is generally treated as usable for around 28–30 days. Keep it cold, keep it out of light, and swab the stopper before every draw.

What's the difference between tirzepatide and semaglutide dosing?

They are not interchangeable. Tirzepatide runs 2.5–15 mg weekly; semaglutide runs 0.25–2.4 mg weekly. Do not convert one to the other by ratio — switch under clinical supervision.

Tirzepatide reference page Check interactions Semaglutide vs tirzepatide

Educational tool only — not medical advice. Verify every dose with your prescriber and follow sterile technique. See our medical disclaimer.

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