How to Use This Calculator
Pick semaglutide or tirzepatide, then enter the vial size in mg, the bacteriostatic water you added and the weekly dose in mg. Choose the syringe size and click Calculate. You get the units and mL to draw, the concentration, how many weekly doses the vial holds and how long it lasts.
Semaglutide mg to Units
Units for example amounts at two concentrations. 2.5 mg/mL is, for example, 5 mg in 2 mL. 5 mg/mL is, for example, 10 mg in 2 mL.
| Amount | At 2.5 mg/mL | At 5 mg/mL |
|---|---|---|
| 0.25 mg | 10 units | 5 units |
| 0.5 mg | 20 units | 10 units |
| 1 mg | 40 units | 20 units |
| 1.5 mg | 60 units | 30 units |
| 2 mg | 80 units | 40 units |
Semaglutide Mixing Calculator: Draw Volume at Different Water Volumes
The table shows the math for a 10 mg semaglutide vial. The draw column uses a 0.25 mg dose only because it is the worked example on this page. Change the numbers in the calculator above to match your own vial and dose.
| Bac water added | Concentration | Draw for 0.25 mg | Units |
|---|---|---|---|
| 1 mL | 10 mg/mL | 0.025 mL | 2.5 units |
| 2 mL | 5 mg/mL | 0.05 mL | 5 units |
| 3 mL | 3.33 mg/mL | 0.075 mL | 7.5 units |
More water gives a lower concentration and a larger draw, while the number of doses stays at 10 / 0.25 = 40 in every row.
Semaglutide Vial Sizes: 5 mg, 10 mg and 15 mg at 2 mL
The concentration depends on the vial size. The table keeps the water at 2 mL and the dose at 0.25 mg, so you can see how the vial size changes the draw and the dose count.
| Vial size | Concentration at 2 mL | Draw for 0.25 mg | Doses per vial |
|---|---|---|---|
| 5 mg | 2.5 mg/mL | 0.1 mL (10 units) | 20 |
| 10 mg | 5 mg/mL | 0.05 mL (5 units) | 40 |
| 15 mg | 7.5 mg/mL | 0.033 mL (3.3 units) | 60 |
Doses per vial is the vial mg divided by the dose in mg, rounded down. A larger vial in the same water is more concentrated, so the same dose is a smaller draw.
Looking for a Tirzepatide Calculator?
This page is for semaglutide. For tirzepatide, use the Tirzepatide Calculator, which converts a tirzepatide dose in mg into U-100 syringe units and mL from the vial size and bac water.
Why the Draw Changes When the Amount Changes
The units to draw depend on two numbers: the amount in mg and the concentration of the vial. Change either one and the draw changes, even when the vial stays the same. Recalculate whenever the amount changes rather than adjusting an old draw by eye. If you need to mix a new vial, the Peptide Reconstitution Calculator works out the concentration, and the Peptide Vial Yield Calculator shows how far a vial goes.
Who Should Use This
Researchers working with mixed vials of semaglutide or tirzepatide who need the syringe draw for a weekly dose in mg.
What This Calculator Does
The Semaglutide and Tirzepatide Dosage Calculator turns a vial size, the bacteriostatic water added and a weekly dose in mg into the draw in units and mL on a U-100 syringe. It also shows the concentration and how many weekly doses the vial holds.
Formula Used
Concentration (mg/mL) = Vial size (mg) / BAC water (mL)Volume per dose (mL) = Weekly dose (mg) / ConcentrationUnits to draw = Volume (mL) x 100 (U-100 syringe)Doses per vial = FLOOR(Vial size / Weekly dose)Example Calculation
Limitations
This is a unit-conversion tool, not dosing guidance. It assumes the whole vial dissolves and a U-100 syringe, and it ignores dead space and draw loss. Branded pens come ready to use, so this calculator does not apply to them.
Frequently Asked Questions
How many units is 0.25 mg of semaglutide?
At 2.5 mg/mL, for example 5 mg in 2 mL, it is 10 units. At 5 mg/mL, for example 10 mg in 2 mL, it is 5 units.
How do I convert units back to mg?
Divide the units by 100 to get mL, then multiply by the concentration in mg/mL. 20 units at 2.5 mg/mL is 0.2 mL x 2.5 = 0.5 mg.
How long will my vial last?
Divide the vial's milligrams by the weekly dose and round down. A 10 mg vial at 0.25 mg a week holds 40 doses, and a 20 mg tirzepatide vial at 5 mg a week holds 4.
What is the difference between semaglutide and tirzepatide?
Semaglutide acts on the GLP-1 receptor. Tirzepatide acts on both the GLP-1 and GIP receptors. The injectable forms of both are given once a week, but their doses are on different scales, so always check which compound you selected before calculating.
How does a semaglutide mixing calculator work?
It divides the mg in the vial by the mL of bacteriostatic water you added to get the concentration in mg per mL. It then divides the dose in mg by that concentration to get the draw in mL, and multiplies by 100 to get units on a U-100 syringe. Changing the water volume changes the concentration and the draw, but not the number of doses in the vial. This is arithmetic only, not a recommended amount.
Does this semaglutide dosage calculator work for 5 mg and 10 mg vials?
Yes. Enter the mg printed on your vial, the bac water you added and the dose in mg. A 5 mg vial in 2 mL is 2.5 mg per mL and a 10 mg vial in 2 mL is 5 mg per mL, so the same dose is a larger draw from the 5 mg vial. The calculator cannot check what is in a vial, so use the figures on your own label.