HGH Calculator

Convert your prescribed HGH dose in IU to syringe units. Defaults to the standard 3 IU/mg potency - override only if your vial label says otherwise.

Last reviewed 2 May 2026

Vial strength (IU)

Total IU in the vial. Common HGH vials are 10, 12 or 15 IU; larger vials come in 20 or 30 IU.

BAC water added (mL)

Volume of bacteriostatic water you reconstituted with. 1 mL is most common for HGH.

Dose (IU)

The dose your prescriber specified, in IU. Common HGH doses are 1 to 4 IU.

Advanced: change potency

HGH is 3 IU/mg by international convention. Only change this if your vial label specifies a different potency.

Syringe diagram showing the pull line

How the HGH maths works

HGH is measured in international units (IU), but reconstitution maths runs on concentration. The calculator converts your vial's IU to milligrams using the potency - 3 IU per milligram by international convention - then divides by the bacteriostatic water you added to get the concentration in IU per millilitre. Your dose in IU divided by that concentration gives the millilitres to draw, and multiplying by 100 reads the units on a U-100 insulin syringe.

Adding more bacteriostatic water makes a weaker solution, so each dose is a larger, easier-to-measure volume; less water makes a stronger solution and a smaller draw. Either is fine as long as you enter the actual volume you used.

Choosing a diluent

Bacteriostatic water - sterile water with 0.9% benzyl alcohol - is the usual choice for a multi-dose vial, because the preservative lets you draw from it over about 28 days in the fridge. Sterile water has no preservative, so a vial reconstituted with it is single-use and should not be kept. People who react to benzyl alcohol sometimes use sterile water or a 0.9% sodium chloride (saline) diluent instead. Whatever you use, follow your pharmacy label.

HGH calculator FAQ

What is the 3 IU/mg potency?

It is the international conversion between international units and milligrams for somatropin - 1 mg is about 3 IU. The calculator uses it by default; only change it if your vial label states a different potency.

How much bacteriostatic water should I add?

Whatever your pharmacy label specifies. If it does not, 1 mL is the most common choice for HGH. Enter the actual volume you used so the units are right.

Which syringe do the units assume?

A U-100 insulin syringe, where 1 mL is 100 units. Check the markings on your own syringe before drawing.

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