Last updated: May 2026
Semaglutide Dosage Calculator
About this calculator
The semaglutide draw volume calculator converts a prescribed dose into the volume to draw from a compounded vial using Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). Designed for people using compounded semaglutide vials with an insulin syringe — not pre-filled branded 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 vial concentration using the preset buttons or enter a custom value. Use the dose slider to set your dose. The draw volume and U-100 syringe units update instantly.
The calculator assumes a U-100 insulin syringe (1 unit = 0.01 mL). Always verify the drawn volume against your syringe markings before injecting.
Worked example
Example — 0.5 mg dose from a 5 mg/mL vial
Vial concentration: 5 mg/mL
Prescribed dose: 0.5 mg
Draw = 0.5 ÷ 5 = 0.10 mL = 10 units (U-100 syringe)
Example — 1.0 mg dose from a 2.5 mg/mL vial
Vial concentration: 2.5 mg/mL
Prescribed dose: 1.0 mg
Draw = 1.0 ÷ 2.5 = 0.40 mL = 40 units (U-100 syringe)
Common dose reference table
| Dose | 2.5 mg/mL vial | 5 mg/mL vial | 10 mg/mL vial |
|---|
| 0.25 mg | 0.10 mL (10 U) | 0.05 mL (5 U) | 0.025 mL (3 U) |
| 0.5 mg | 0.20 mL (20 U) | 0.10 mL (10 U) | 0.05 mL (5 U) |
| 1.0 mg | 0.40 mL (40 U) | 0.20 mL (20 U) | 0.10 mL (10 U) |
| 1.7 mg | 0.68 mL (68 U) | 0.34 mL (34 U) | 0.17 mL (17 U) |
| 2.4 mg | 0.96 mL (96 U) | 0.48 mL (48 U) | 0.24 mL (24 U) |
Frequently asked questions
How do I calculate semaglutide dosage from a compounded vial?
Divide your prescribed dose in mg by your vial concentration in mg/mL. For example, a 0.5 mg dose from a 5 mg/mL vial equals 0.5 ÷ 5 = 0.10 mL, which is 10 units on a U-100 insulin syringe. The calculator does this division automatically. Always confirm the concentration printed on your specific pharmacy vial, as compounded semaglutide concentrations vary between pharmacies.
What concentrations does compounded semaglutide come in?
Compounded semaglutide commonly comes in concentrations of 2.5 mg/mL, 5 mg/mL, and 10 mg/mL, though the exact concentration depends on your compounding pharmacy. The concentration is always printed on the vial label. This calculator supports all three common concentrations plus a custom input field for any pharmacy-specific concentration. Always use the concentration stated on your own vial — do not assume a standard concentration.
How many units should I draw on an insulin syringe?
On a standard U-100 insulin syringe, each unit mark equals 0.01 mL. To find the number of units, multiply your draw volume in mL by 100. For example, 0.10 mL = 10 units; 0.20 mL = 20 units. The calculator computes this automatically. Note that some syringes are U-40 (each unit = 0.025 mL) — using the wrong syringe type will give you the wrong dose. This calculator assumes U-100 throughout.
Is this calculator suitable for Ozempic or Wegovy pens?
No. This calculator is designed for compounded semaglutide supplied in multi-dose vials that you draw from yourself using an insulin syringe. Brand-name pens (Ozempic, Wegovy) are pre-dosed and do not require draw volume calculations — the dose is dialled directly on the pen device. This calculator applies only to vial-and-syringe preparations from compounding pharmacies.
Dosing guide
Learn about dose escalation, injection preparation, and storage in the full reference guide. Semaglutide Dosing Guide →
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