HCG Dosing: Fertility Protocols vs TRT Support
Last updated: June 2026
Human chorionic gonadotropin (HCG) shows up in two very different number ranges depending on the goal: relatively high, frequent doses described in the literature for restarting sperm production or restoring fertility, versus small, low-frequency doses used alongside testosterone to keep the testes working. This guide explains those reported dose ranges and the IU→syringe-unit reconstitution maths behind each — it is an education and arithmetic tool, not medical advice, and any actual dose, schedule, and route must come from your prescriber.
Have a vial strength, water volume, and target IU? Convert any HCG dose to exact mL and U-100 syringe units instantly.
HCG calculator →TL;DR — key takeaways
- Two different ranges. Fertility / hypogonadotropic restart protocols in the literature describe doses in the low thousands of IU, two to three times a week. On-TRT testicular support is typically described at a few hundred IU, often a couple of times a week. These are illustrative of the ranges seen in studies and labels — not a prescription.
- Units follow concentration, not goal. Whether 250 IU or 1,500 IU lands as 5 units or 60 units on the syringe depends entirely on how much bacteriostatic water you reconstituted the vial with.
- Same molecule, same maths. The IU→mL→units arithmetic is identical for both use-cases. Only the target IU changes.
- Evidence has limits. Much HCG-on-TRT dosing is described in small studies and clinical practice, not large trials; fertility restart evidence is stronger but still individualised.
Why the two dose ranges diverge
HCG mimics luteinising hormone (LH). LH is the signal that tells the testicular Leydig cells to make testosterone and helps maintain the local environment for sperm production. The two clinical goals ask different things of that signal.
For fertility and hypogonadotropic restart, the aim is to drive meaningful intratesticular testosterone and support spermatogenesis — often in someone whose own gonadotropins are suppressed or absent. Reported protocols for restoring spermatogenesis describe HCG in the region of 1,000–2,500 IU two to three times weekly, sometimes later combined with FSH-type therapy. The doses are higher because the goal is a full physiological restart, not a top-up.
For testicular support during TRT, exogenous testosterone shuts down the body's own LH, so the testes lose their signal and can shrink and stop producing intratesticular testosterone. Low-dose HCG is described as a way to keep that local signal alive. A frequently cited study (Coviello et al.) found that small HCG doses — on the order of 250–500 IU every other day in that experimental setting — helped preserve intratesticular testosterone in men on testosterone. In everyday practice, a few hundred IU a couple of times a week is the range most often described. The point is maintenance, not a restart, so the numbers are much smaller.
Reported dose ranges at a glance
The table summarises the ranges described in the literature and labels for each goal. It is illustrative only — your prescriber sets the actual figure, and individual protocols vary widely.
| Property | Fertility / restart | TRT testicular support |
|---|---|---|
| Goal | Restore spermatogenesis / fertility | Preserve testes & intratesticular testosterone on TRT |
| Typical reported dose | ~1,000–2,500 IU | ~250–500 IU |
| Typical frequency | 2–3× / week | 2–3× / week (some EOD) |
| Used with | Sometimes FSH/hMG later | Testosterone ester |
| Evidence strength | Moderate (restart studies) | Limited / small studies |
| Route | Subcutaneous (per prescriber) | Subcutaneous (per prescriber) |
Figures reflect ranges in published studies and product labelling for HCG; they are not a recommendation. Compounded vials are drawn and reconstituted manually, so you must work out the draw volume yourself — and confirm everything against your own vial label and prescriber instructions.
The two ranges, visualised
The same molecule, plotted on one IU axis — support sits low, fertility sits several times higher per dose.
How to turn any HCG dose into syringe units
HCG is dosed in international units (IU), but you read units on a U-100 insulin syringe, where 100 units = 1 mL. The conversion never changes: work out the concentration (IU/mL = vial IU ÷ water mL), divide your dose by it to get mL, then multiply by 100 to get syringe units.
Worked example 1 — TRT support dose
A 5,000 IU vial reconstituted with 5 mL bacteriostatic water gives 5000 ÷ 5 = 1,000 IU/mL. Target support dose 500 IU.
500 IU ÷ 1,000 IU/mL = 0.5 mL. 0.5 mL × 100 = 50 units.
Draw 50 units on a U-100 syringe.
Worked example 2 — same vial, smaller support dose
Same 1,000 IU/mL concentration, target 250 IU.
250 ÷ 1,000 = 0.25 mL. 0.25 mL × 100 = 25 units.
Draw 25 units — a quarter of a 1 mL syringe.
Worked example 3 — fertility-range dose
Same 1,000 IU/mL vial, target fertility-range dose 1,500 IU.
1,500 ÷ 1,000 = 1.5 mL. That is more than a 1 mL syringe holds, so it needs two draws — or a more concentrated vial.
Reconstitute the same 5,000 IU with 2 mL instead: 5000 ÷ 2 = 2,500 IU/mL. Now 1,500 ÷ 2,500 = 0.6 mL = 60 units, one clean draw.
More water = lower concentration = more units; less water = higher concentration = fewer units.
IU-to-units reference chart
Common HCG doses for each goal, shown as units on a U-100 syringe at two reconstitution choices of a 5,000 IU vial. Always confirm against your own vial.
| Dose (IU) | 5,000 IU in 5 mL (1,000 IU/mL) | 5,000 IU in 2 mL (2,500 IU/mL) |
|---|---|---|
| 250 (support) | 25 units | 10 units |
| 500 (support) | 50 units | 20 units |
| 1,000 (fertility) | 100 units | 40 units |
| 1,500 (fertility) | — (over 1 mL) | 60 units |
| 2,500 (fertility) | — (over 1 mL) | 100 units |
Notice the dashes: at 1,000 IU/mL, anything above 1,000 IU per dose exceeds a 1 mL syringe, which is exactly why higher-dose fertility protocols are often reconstituted with less water (a higher concentration). If your draw exceeds 1 mL, a stronger reconstitution — or splitting the draw — is the usual fix.
How this is calculated
Every number above uses two facts only: a U-100 syringe holds 100 units per mL, and concentration is IU divided by the water volume you added. There is no separate "fertility formula" or "support formula" — the arithmetic is identical, and only the target IU your prescriber set is different. The HCG calculator automates exactly this so you can sanity-check the chart above against your own vial. None of this is medical advice; it is the maths behind a dose someone qualified has chosen for your situation, and the evidence behind the ranges — especially for on-TRT support — is still limited.
Frequently asked questions
Why is the fertility dose so much higher than the TRT-support dose?
The goals differ. Restarting spermatogenesis aims to drive a full physiological response, so reported protocols use higher per-dose IU. On-TRT support only tries to keep the existing testicular signal alive, so the described ranges are much smaller. Both are illustrative of the literature, not a prescription.
Does a higher IU dose always mean more syringe units?
No. Units depend on concentration. A 1,500 IU dose from a 2,500 IU/mL vial is 60 units, while a 500 IU dose from a 1,000 IU/mL vial is 50 units. The reconstitution choice, not the dose alone, sets the syringe mark.
Can I just copy someone else's HCG units?
Only if their vial strength and water volume exactly match yours. The same unit mark can represent very different IU if the concentration differs. Always recalculate for your own vial.
Is the on-TRT support range well proven?
The evidence is limited. Small studies such as Coviello et al. support the idea that low-dose HCG preserves intratesticular testosterone, but precise dosing is individualised and set by a prescriber, not by general ranges.
Sources
- Chorionic Gonadotropin for Injection Prescribing Information (Fresenius Kabi, DailyMed / FDA label)
- Coviello AD, et al. Low-Dose Human Chorionic Gonadotropin Maintains Intratesticular Testosterone in Normal Men with Testosterone-Induced Gonadotropin Suppression (J Clin Endocrinol Metab 2005)
- Lee JA, Ramasamy R. Indications for the use of human chorionic gonadotropic hormone for the management of infertility in hypogonadal men (Transl Androl Urol 2018)
- Mulhall JP, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline (J Urol 2018)
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline (J Clin Endocrinol Metab 2018)
- Wenker EP, et al. The Use of HCG-Based Combination Therapy for Recovery of Spermatogenesis after Testosterone Use (J Sex Med 2015)
- Ramasamy R, et al. Testosterone supplementation versus clomiphene citrate for hypogonadism: an age matched comparison (J Urol 2014)
- Depenbusch M, et al. Maintenance of spermatogenesis in hypogonadotropic hypogonadal men with human chorionic gonadotropin alone (Eur J Endocrinol 2002)
- Crosnoe LE, et al. Exogenous testosterone: a preventable cause of male infertility (Transl Androl Urol 2013)
- Liu PY, et al. Induction of spermatogenesis and fertility during gonadotropin treatment of gonadotropin-deficient infertile men (J Clin Endocrinol Metab 2009)
- Pfizer. Bacteriostatic Water for Injection prescribing information
- Hsieh TC, et al. Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy (J Urol 2013)
This guide is for general educational purposes only and does not constitute medical advice. Always follow your prescriber’s specific instructions and consult a qualified clinician before changing any protocol.