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HGH dose calculator
Somatropin is prescribed in mg, sold in vials labeled in IU, drawn on a syringe marked in insulin units and dialed on pens in mg again. This calculator converts a dose you already have between all four, then tells you how many doses your vial or pen cartridge holds and whether it will outlast its in-use window. For the mixing step itself, see how to reconstitute HGH.
1. Your dose
Enter the dose you have been prescribed, in whichever unit it was written. Runs in your browser; nothing is sent anywhere.
Prescription written per kg of body weight?
Divides a weekly mg/kg figure from your prescription across your injections per week, then fills the dose above.
2. Your product
Pick a branded cartridge or pen (strengths from the current US labels), or a vial you mix yourself.
Four units, one dose
Many HGH dosing mistakes are unit mistakes. There are four units in play. mg is what US prescriptions and branded pens use. IU (international units) is what most vials sold outside a pharmacy are labeled in and what forum protocols are written in. The two are linked by a fixed convention of 3 IU per mg, which Lilly's label for Humatrope spells out: the 6 mg cartridge is 18 IU, the 12 mg is 36 IU and the 24 mg is 72 IU. Insulin units on a U-100 syringe measure volume, not hormone: 100 units is 1 mL, whatever is in it. And clicks or dial settings on a pen are the manufacturer's own increments, set out in each pen's instructions for use.
So "2 IU" is 0.67 mg of hormone. On a syringe it is 20 units if the vial is at 10 IU per mL, about 16.7 units at 12 IU per mL and 40 units at 5 IU per mL. On a pen it is a 0.67 mg dial setting, if the pen's increments allow it. The same dose has a different number on every device, which is why this calculator asks for the device.
How much is 2 IU of HGH on an insulin syringe?
Insulin units for a dose you mix yourself are dose ÷ concentration × 100, where concentration is the vial's IU divided by the water you added:
| Vial + water | Concentration | 1 IU | 2 IU | 3 IU | 4 IU |
|---|---|---|---|---|---|
| 10 IU + 1 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
| 10 IU + 2 mL | 5 IU/mL | 20 u | 40 u | 60 u | 80 u |
| 12 IU + 1 mL | 12 IU/mL | 8.3 u | 16.7 u | 25 u | 33.3 u |
| 15 IU + 1.5 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
| 36 IU + 3 mL | 12 IU/mL | 8.3 u | 16.7 u | 25 u | 33.3 u |
| 36 IU + 3.6 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
At 10 IU per mL the conversion collapses to insulin units = IU × 10, which is why it is the concentration most people mix to. The reconstitution guide covers the mixing.
Branded pens and cartridges
Pharmacy somatropin in the US comes as a cartridge or prefilled pen at a fixed concentration. You set the dose in mg on the pen rather than drawing it. What varies between products is the strength, the volume and how long the cartridge may be used once started:
| Product | Strengths | Concentration | In use after first dose |
|---|---|---|---|
| Omnitrope cartridge | 5 mg/1.5 mL, 10 mg/1.5 mL | 3.33, 6.67 mg/mL | Up to 28 days, refrigerated |
| Genotropin cartridge | 5 mg, 12 mg (two-chamber, mixed in the pen) | 5, 12 mg/mL | Up to 28 days, refrigerated |
| Norditropin FlexPro | 5 mg/1.5 mL, 10 mg/1.5 mL, 15 mg/1.5 mL, 30 mg/3 mL | 3.33, 6.67, 10, 10 mg/mL | 4 weeks refrigerated, or 3 weeks at up to 25 °C |
| Humatrope cartridge | 6 mg, 12 mg, 24 mg (mixed with ~3 mL diluent) | 2.08, 4.17, 8.33 mg/mL | Up to 28 days, refrigerated |
The in-use window matters more than people expect at low doses. A Norditropin 10 mg pen at 0.3 mg a day holds 33 doses, but the label's 4-week refrigerated window closes at day 28 with about 1.6 mg still in it. A 5 mg pen would have run 16 days at the same dose and wasted nothing. The calculator flags this case. Each pen also needs priming and has its own dial increments, so follow the instructions for use that come with it, which the calculator cannot see.
What the labels say about dose
Every US somatropin label sets dosing by indication and adjusts it against IGF-1 and response. For adult growth hormone deficiency they converge on the same non-weight-based start:
| Label | Adult GHD, non-weight-based | Adult GHD, weight-based | Pediatric GHD |
|---|---|---|---|
| Genotropin | ~0.2 mg/day (0.15–0.30) | start ≤0.04, up to ≤0.08 mg/kg/week | 0.16–0.24 mg/kg/week |
| Omnitrope | ~0.2 mg/day (0.15–0.30) | start ≤0.04, up to ≤0.08 mg/kg/week | 0.16–0.24 mg/kg/week |
| Norditropin | ~0.2 mg/day (0.15–0.30) | 0.004 mg/kg/day, max 0.016 | 0.17–0.24 mg/kg/week |
| Humatrope | ~0.2 mg/day (0.15–0.30) | 0.006 mg/kg/day, max 0.0125 | 0.18–0.30 mg/kg/week |
The labels increase the adult dose by 0.1 to 0.2 mg a day every 1 to 2 months. Two numbers are worth holding next to each other: the label's adult starting dose of 0.2 mg is about 0.6 IU, while the 1 to 4 IU a day commonly reported online for body composition is 0.33 to 1.33 mg, up to about seven times that. Those figures come from off-label use, not from the labels. The Omnitrope label describes fluid retention (swelling, joint pain, carpal tunnel symptoms) as dose dependent and says insulin sensitivity can fall, particularly at higher doses. This table is reference material for a diagnosed deficiency under a prescriber, not a dose to choose for yourself.
Somatropin is a prescription medicine, approved for growth hormone deficiency and a short list of related conditions, not for body composition or anti-aging. In the United States, distributing it, or possessing it with intent to distribute, for a non-approved use is a federal offense under 21 U.S.C. 333(e). Vials sold outside a pharmacy carry no guarantee of strength, purity or sterility, so the arithmetic on this page is only as good as the label on the vial. HGH affects glucose handling and fluid balance, which is why the labels call for monitoring. The symptoms listed at the top of this page are reasons to stop and see a doctor, as is an injection site that turns red, hot or increasingly painful, or a fever after injecting. This calculator converts numbers; it is not medical advice and not a recommendation to use somatropin.
Log it once, stop doing this math
OptiPin logs each injection with its site, tracks what is left in the vial or cartridge and warns you before it runs out or passes its in-use date. Bloodwork such as IGF-1 and glucose sits on the same timeline as your doses. iOS, on-device, no account.
Get OptiPinFrequently asked questions
How many IU is 1 mg of HGH?
About 3 IU. The convention for recombinant somatropin is 3 IU per mg. Lilly's US label for Humatrope states it directly: the 6 mg cartridge is 18 IU, the 12 mg is 36 IU and the 24 mg is 72 IU. So 1 IU is about 0.33 mg and 2 IU is about 0.67 mg.
How much is 2 IU of HGH on an insulin syringe?
It depends entirely on the concentration in the vial. At 10 IU per mL it is 20 units on a U-100 syringe. A 36 IU vial mixed with 3 mL is 12 IU per mL, so 2 IU is about 16.7 units. With 2 mL in a 10 IU vial it is 40 units. Branded pens are not drawn with a syringe at all: the pen is dialed in mg. On a pen, 2 IU is about 0.67 mg.
How long does an HGH pen cartridge last?
Whichever comes first: running out, or the labeled in-use window. Omnitrope, Genotropin and Humatrope cartridges are labeled for up to 28 days refrigerated after first use. Norditropin FlexPro is labeled for 4 weeks refrigerated or 3 weeks at up to 25 °C. A 10 mg Norditropin pen at 0.3 mg a day holds 33 doses, but the window closes at day 28 with about 1.6 mg left.
What dose do the US labels start adults on?
For adult growth hormone deficiency, the Genotropin, Omnitrope, Norditropin and Humatrope labels all give a non-weight-based starting dose of about 0.2 mg a day (range 0.15 to 0.30 mg), adjusted every 1 to 2 months by 0.1 to 0.2 mg a day against IGF-1 and response. 0.2 mg is about 0.6 IU. That is label information for a diagnosed deficiency, prescribed and monitored by a clinician, not a recommendation.
Does this calculator tell me what dose to take?
No. It converts a dose you already have into IU, mg, syringe units, doses and days. The dose itself belongs to a prescriber. Somatropin is a prescription medicine. In the US, distributing it for a non-approved use is a federal offense under 21 U.S.C. 333(e).
Sources
- HUMATROPE (somatropin) for injection – US prescribing information, DailyMed. Cartridge strengths in mg and IU (6 mg = 18 IU), reconstituted concentrations, adult and pediatric dosing, 28-day in-use storage.
- NORDITROPIN (somatropin) injection – US prescribing information, DailyMed. FlexPro pen strengths, adult and pediatric dosing, in-use storage of 4 weeks refrigerated or 3 weeks at up to 25 °C.
- GENOTROPIN (somatropin) – US prescribing information, DailyMed. 5 mg and 12 mg two-chamber cartridges, adult and pediatric dosing, 28-day in-use storage.
- OMNITROPE (somatropin) – US prescribing information, DailyMed. 5 mg/1.5 mL and 10 mg/1.5 mL cartridges, dosing, 28-day cartridge in-use storage and the warnings section (intracranial hypertension, fluid retention, glucose intolerance, pancreatitis, slipped capital femoral epiphysis).
- 21 U.S.C. 333(e) – distribution of human growth hormone, Legal Information Institute, Cornell Law School.
Product strengths and in-use windows are from the US labels as published on DailyMed in October 2026. Products and strengths differ by country, so check the leaflet in your own pack.
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HGH reconstitution guide · Somatropin profile · TRT vs HGH vs peptides · Tesamorelin reconstitution · MK-677 tracker · IU to mL calculator · Vial longevity calculator · All calculators · Beyond-use date calculator (in-use pen windows)