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GLP-1 Dose Calculator

The three GLP-1 compounds, with the same arithmetic as every other reconstitution page: a vial strength and a water volume give a concentration, and a dose gives the mark it reaches on a U-100 syringe. The vial-size chips come from the sizes tracked across vendors, not from generic examples.

Last reviewed: September 21, 2026

Vial strength and water volume give a concentration; a dose then gives the unit mark it corresponds to.

Vial sizes vendors carry — tap to fill:

How much bac water?
Syringe barrel

For research purposes only. Always verify calculations independently before use.

How the arithmetic works

  • Concentration (mg/mL) = vial strength (mg) ÷ water volume (mL)
  • Syringe units = (dose (mg) ÷ concentration (mg/mL)) × 100

The same two steps apply to semaglutide, tirzepatide and retatrutide alike — the arithmetic doesn’t change between compounds, only the vial sizes each one is actually sold in.

Worked example

A 10 mg vial reconstituted with 2 mL of water, for a 2 mg dose:

Concentration10 mg ÷ 2 mL = 5 mg/mL
Draw volume2 mg ÷ 5 mg/mL = 0.4 mL
Syringe units0.4 mL × 100 = 40 units

Enter the same three numbers into the calculator above and it returns the same figures, for any of the three compounds.

FAQ

glp1 dose calculator semaglutide tirzepatide retatrutide
This page's calculator covers all three GLP-1 compounds Prof. Peptide tracks — semaglutide, tirzepatide and retatrutide — with the same reconstitution arithmetic: a vial strength and a water volume give a concentration, and a dose gives the mark it reaches on a U-100 syringe.
How many units is my GLP-1 dose?
It depends on the vial's concentration, which is its strength divided by the water volume used to reconstitute it. A 10 mg vial in 2 mL of water (5 mg/mL) reads a 2 mg dose as 40 units on a U-100 syringe. Each compound's own dedicated calculator lists the vial sizes actually tracked across vendors for that specific compound.
Is the arithmetic different for semaglutide, tirzepatide and retatrutide?
No — concentration equals vial strength divided by water volume, and syringe units equal the dose divided by that concentration, times 100, for all three. What differs between the compounds is the vial sizes vendors actually sell, not the underlying math.

For a specific compound’s own vial sizes (as tracked across vendors), the units chart by dose, and its dosing evidence, see its dedicated page: semaglutide, tirzepatide, or retatrutide. For the published label and trial dose schedules side by side, see the GLP-1 titration schedule.