Last updated: May 2026
HCG Dosage Calculator
About this calculator
The HCG dosage calculator converts your prescribed IU dose into the exact volume to draw from a reconstituted vial using the formula Volume (mL) = Dose (IU) ÷ Concentration (IU/mL). Enter your vial strength, how much bacteriostatic water you used for reconstitution, and your prescribed dose to get your draw volume instantly. Free, private, no login required.
How to use this calculator
You need three pieces of information: your vial strength (in IU), how much bacteriostatic water (BAC water) you used to reconstitute it, and your prescribed dose per injection (in IU).
Select your vial strength using the preset chips (2,000 / 5,000 / 10,000 IU are the most common). Select the BAC water volume you used — 1 mL and 2 mL are standard choices. The calculator derives the concentration automatically and shows it below the BAC water selector.
Adjust the dose per injection slider to your prescribed amount. The output shows your draw volume in mL and in U-100 insulin syringe units.
Worked example
Example — 250 IU dose from 5,000 IU vial
Vial strength: 5,000 IU
BAC water added: 1 mL
Concentration: 5,000 IU/mL
Prescribed dose: 250 IU
Draw = 250 ÷ 5000 = 0.05 mL = 5 units (U-100)
Example — 500 IU dose from 5,000 IU vial, 2 mL BAC water
Vial strength: 5,000 IU
BAC water added: 2 mL
Concentration: 2,500 IU/mL
Prescribed dose: 500 IU
Draw = 500 ÷ 2500 = 0.20 mL = 20 units (U-100)
Common draw volumes by vial and dose
| Dose (IU) | 5,000 IU / 1 mL (5,000 IU/mL) | 5,000 IU / 2 mL (2,500 IU/mL) | 10,000 IU / 2 mL (5,000 IU/mL) |
|---|
| 125 IU | 0.025 mL (2.5 U) | 0.050 mL (5 U) | 0.025 mL (2.5 U) |
| 250 IU | 0.050 mL (5 U) | 0.100 mL (10 U) | 0.050 mL (5 U) |
| 500 IU | 0.100 mL (10 U) | 0.200 mL (20 U) | 0.100 mL (10 U) |
| 1000 IU | 0.200 mL (20 U) | 0.400 mL (40 U) | 0.200 mL (20 U) |
HCG in TRT protocols
HCG (Human Chorionic Gonadotropin) is a glycoprotein hormone that mimics the action of luteinising hormone (LH). In men on TRT, the hypothalamic–pituitary axis is suppressed by exogenous testosterone, meaning the testes receive no LH signal and cease producing testosterone and sperm. HCG binds to the LH receptor in the Leydig cells of the testes, stimulating intra-testicular testosterone production and maintaining testicular volume.
The most common TRT adjunct protocol is 250 IU subcutaneously, 2–3 times per week. Some fertility protocols use higher doses (500–1,000 IU) for more aggressive spermatogenesis support. HCG must be prescribed and managed by a qualified clinician. This calculator performs unit conversion only — it does not provide dosing guidance.
Frequently asked questions
How is HCG different from testosterone injections?
Testosterone injections replace testosterone directly; HCG works upstream by stimulating the testes to produce their own testosterone and sperm. HCG is used as an adjunct to TRT (not a replacement) to preserve testicular function, fertility, and testicular volume that would otherwise be suppressed by exogenous testosterone. The two are often administered on the same injection days.
What is the formula the calculator uses?
Draw volume (mL) = Dose (IU) ÷ Concentration (IU/mL). Concentration is derived from: Concentration (IU/mL) = Vial strength (IU) ÷ BAC water added (mL). These are standard pharmaceutical dilution calculations. The calculator applies them exactly with no adjustments or estimations.
Should I use 1 mL or 2 mL of BAC water?
It depends on your dose. Adding 1 mL to a 5,000 IU vial gives 5,000 IU/mL — a 250 IU dose draws just 5 units on a U-100 syringe (0.05 mL), which is measurable but small. Adding 2 mL gives 2,500 IU/mL — the same dose now draws 10 units (0.10 mL), which is easier to measure accurately. In general, aim for a draw volume of at least 10 units per injection for precision. Use the calculator to find the BAC water volume that gives a comfortable draw for your dose.
Can I use HCG with semaglutide or tirzepatide?
HCG is a hormone therapy used in endocrine contexts (TRT, fertility); semaglutide and tirzepatide are GLP-1 receptor agonists used for metabolic/weight-loss purposes. They work through entirely different mechanisms and are typically not co-administered unless specifically indicated by your prescriber. Any combination therapy requires clinician oversight. Use the relevant calculator for each medication separately.
How do I read very small draw volumes on a syringe?
On a U-100 insulin syringe, 1 unit = 0.01 mL. A draw of 5 units (0.05 mL) is at the 5-unit mark on a standard 0.3 mL or 0.5 mL syringe. Standard 0.3 mL syringes have 1-unit graduation marks, making small draws like 5 units measurable. Pull the plunger past your target and push back to the exact mark to clear air from the needle tip. For very precise small draws, consider using 2 mL of BAC water (lower concentration) to increase the draw volume.
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