Last updated: May 2026

Tirzepatide Dosage Calculator

Quick answer: A 5 mg dose from a 10 mg/mL compounded vial is 0.50 mL = 50 units on a U-100 syringe. Formula: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL), and units = mL × 100.

About this calculator

The tirzepatide draw volume calculator converts a prescribed dose into the volume to draw from a compounded vial using Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). Built for people using compounded tirzepatide vials — not pre-filled Mounjaro or Zepbound pens. Supports 2.5, 5, and 10 mg/mL concentrations plus custom entries. Free, instant, no login.

How to use this calculator

You need two pieces of information: your vial concentration (printed on the pharmacy label in mg/mL) and your prescribed dose in mg.

Select your concentration using the preset buttons, or enter a custom value if your pharmacy uses a different concentration. Set your dose using the slider. Draw volume and U-100 units update instantly.

Always verify the drawn volume against your syringe markings before injecting. This calculator assumes a U-100 insulin syringe (1 unit = 0.01 mL).

Worked example

Example — 5 mg dose from a 10 mg/mL vial

Vial concentration: 10 mg/mL

Prescribed dose: 5 mg

Draw = 5 ÷ 10 = 0.50 mL = 50 units (U-100 syringe)

Example — 2.5 mg dose from a 5 mg/mL vial

Vial concentration: 5 mg/mL

Prescribed dose: 2.5 mg

Draw = 2.5 ÷ 5 = 0.50 mL = 50 units (U-100 syringe)

Common dose reference table

Dose2.5 mg/mL vial5 mg/mL vial10 mg/mL vial
2.5 mg1.00 mL (100 U)0.50 mL (50 U)0.25 mL (25 U)
5 mg2.00 mL (200 U)1.00 mL (100 U)0.50 mL (50 U)
7.5 mg3.00 mL (300 U)1.50 mL (150 U)0.75 mL (75 U)
10 mg4.00 mL (400 U)2.00 mL (200 U)1.00 mL (100 U)
12.5 mg5.00 mL (500 U)2.50 mL (250 U)1.25 mL (125 U)
15 mg6.00 mL (600 U)3.00 mL (300 U)1.50 mL (150 U)

Typical tirzepatide titration schedule

Standard compounded vial protocol. Your prescriber sets your actual schedule — titration timing and doses vary. Full titration guide →

0 2.5 5 7.5 10 12.5 15 mg/wk 2.5 mg Wks 1–4 5 mg Wks 5–8 7.5 mg Wks 9–12 10 mg Wks 13–16 12.5 mg Wks 17–20 15 mg Wk 21+ Typical schedule — your prescriber sets actual timing and doses

Frequently asked questions

How do I calculate tirzepatide dosage from a compounded vial?
Divide your prescribed dose in mg by your vial concentration in mg/mL. For example, a 5 mg dose from a 10 mg/mL vial equals 5 ÷ 10 = 0.50 mL, which is 50 units on a U-100 insulin syringe. The calculator performs this division automatically. Always confirm the concentration on your specific pharmacy label — compounded tirzepatide concentrations vary by pharmacy and the concentration used determines the correct draw volume.
What concentrations does compounded tirzepatide come in?
Compounded tirzepatide is commonly available in concentrations of 2.5 mg/mL, 5 mg/mL, and 10 mg/mL, though individual pharmacies may offer different concentrations. The exact concentration is always stated on the vial label. This calculator supports 2.5, 5, and 10 mg/mL with a custom entry option for other concentrations. Always use the concentration from your own label — do not assume a standard value.
How many units of tirzepatide should I draw on an insulin syringe?
On a standard U-100 insulin syringe, each unit equals 0.01 mL. Multiply your draw volume in mL by 100 to get units. For example, 0.50 mL = 50 units. The calculator computes this automatically. This calculator assumes a U-100 syringe throughout — if you use a U-40 syringe (each unit = 0.025 mL) the unit count will differ. Confirm your syringe type before drawing.
Is this calculator suitable for Mounjaro or Zepbound pens?
No. This calculator is for compounded tirzepatide supplied in vials that you draw from with an insulin syringe. Brand-name autoinjector pens (Mounjaro, Zepbound) are pre-dosed — you simply dial the dose and inject without any draw volume calculation. This tool applies only to compounded vial-and-syringe preparations.
How does tirzepatide dosing differ from semaglutide?
Tirzepatide and semaglutide are both injectable GLP-1 receptor agonists used for weight management, but their dose ranges differ. Tirzepatide starting doses are typically 2.5 mg, escalating up to 15 mg, while semaglutide starting doses are 0.25 mg, escalating up to 2 mg or more depending on the formulation. Tirzepatide also acts on the GIP receptor in addition to GLP-1. For both medications, the draw volume calculation is identical — dose (mg) divided by concentration (mg/mL) — which is what this calculator performs.

Dosing guide

Learn about tirzepatide dose escalation, injection preparation, and vial concentration selection in the full reference guide. Tirzepatide Dosing Guide →

Other calculators

Semaglutide Dosage Calculator Retatrutide Dosage Calculator GLP-1 Titration Calculator BMI Calculator

Related guides

How many units is 5 mg tirzepatide? → Tirzepatide explained simply → Why GLP-1 doses increase over time → How to store GLP-1 medications → What to do if you miss a GLP-1 dose →

How this is calculated

This calculator divides your prescribed dose by the vial concentration to find the injection volume, then converts that volume to insulin-syringe units (volume in mL × 100 for a U-100 syringe). It is arithmetic only — nothing you enter is stored or sent anywhere, and the result is not medical advice. Always confirm your dose with your prescriber.

References

  1. ZEPBOUND (tirzepatide) Prescribing Information — dose titration — FDA / DailyMed, 2023
  2. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1) — N Engl J Med, 2022
  3. FDA Concerns With Unapproved GLP-1 Drugs Used for Weight Loss (incl. compounded tirzepatide) — U.S. FDA
  4. FDA Green List: Protecting Americans From Illegal Imported GLP-1 Drug Ingredients — U.S. FDA

Citations are provided for transparency and education. They do not imply the cited authors or bodies endorse this tool. Always confirm dosing with your prescriber.

Embed this on your site — get embed code →

InjectBuddy/Tirzepatide Dosage Calculator