hCG reconstitution calculator

How this calculator works

Mixed concentration equals the vial's total IU divided by the amount of bacteriostatic water added, in mL. Draw volume equals your prescribed dose in IU divided by that concentration. A U-100 insulin syringe is marked in units, where 100 units equal 1 mL, so the unit marking is the draw volume multiplied by 100.

Why hCG is used alongside TRT

hCG mimics luteinizing hormone and is sometimes prescribed alongside testosterone therapy to help maintain testicular size and function, including fertility, since exogenous testosterone alone can suppress the body's own signals to the testes.

Why the reconstitution volume matters

Unlike pre-mixed testosterone esters, hCG's concentration depends entirely on how much water you add, so two vials of the same size can end up at very different concentrations. Always use the reconstitution volume your prescriber or pharmacy specified, and double check the arithmetic against your own vial label.

Frequently asked questions

What does reconstituting hCG mean?

hCG is typically supplied as a freeze-dried (lyophilized) powder in a vial, measured in international units (IU), that has to be mixed with a liquid, usually bacteriostatic water, before it can be drawn into a syringe. Reconstitution is that mixing step.

How do I calculate the concentration after mixing?

Divide the vial's total IU by the amount of bacteriostatic water you add, in mL. For example, a 5,000 IU vial mixed with 2 mL of water gives a concentration of 2,500 IU per mL.

How do I draw the correct dose once it's mixed?

Divide your prescribed dose in IU by the concentration you calculated to get the draw volume in mL. This tool also converts that volume into U-100 insulin syringe unit markings.

Can this tool tell me how much hCG to take?

No. It only converts a vial size and a prescribed dose your prescriber has already set into a concentration and a draw volume. It does not suggest a dose or a reconstitution volume.