Last updated: May 2026
Tirzepatide Dosage Calculator
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
| Dose | 2.5 mg/mL vial | 5 mg/mL vial | 10 mg/mL vial |
|---|
| 2.5 mg | 1.00 mL (100 U) | 0.50 mL (50 U) | 0.25 mL (25 U) |
| 5 mg | 2.00 mL (200 U) | 1.00 mL (100 U) | 0.50 mL (50 U) |
| 7.5 mg | 3.00 mL (300 U) | 1.50 mL (150 U) | 0.75 mL (75 U) |
| 10 mg | 4.00 mL (400 U) | 2.00 mL (200 U) | 1.00 mL (100 U) |
| 12.5 mg | 5.00 mL (500 U) | 2.50 mL (250 U) | 1.25 mL (125 U) |
| 15 mg | 6.00 mL (600 U) | 3.00 mL (300 U) | 1.50 mL (150 U) |
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.
Dosing guide
Learn about tirzepatide dose escalation, injection preparation, and vial concentration selection in the full reference guide. Tirzepatide Dosing Guide →
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