Last updated: May 2026

HCG Dosage Calculator

Q: 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.

Quick answer: A 250 IU dose from a 5,000 IU vial reconstituted with 1 mL of BAC water (5,000 IU/mL) is 0.05 mL = 5 units on a U-100 syringe. Formula: Volume (mL) = Dose (IU) ÷ Concentration (IU/mL).

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 Testosterone (TRT) protocols

HCG (Human Chorionic Gonadotropin) is a glycoprotein hormone that mimics the action of luteinising hormone (LH). In men on Testosterone (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 Testosterone (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 Testosterone (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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How this is calculated

This calculator divides your prescribed dose by the vial concentration to find the injection volume, then converts that volume to insulin-syringe units (volume in mL × 100 for a U-100 syringe). It is arithmetic only — nothing you enter is stored or sent anywhere, and the result is not medical advice. Always confirm your dose with your prescriber.