Somatropin mg to IU converter
1 mg of somatropin equals approximately 3 IU. The 3 IU per mg conversion is the standard reference value used on every FDA-approved somatropin label, including Genotropin, Humatrope, Norditropin, Saizen, and Omnitrope.
Somatropin mg to IU at 3 IU per mg
Pre-calculated for the standard clinical conversion. Multiply the mg value by 3 to get IU.
| Somatropin (mg) | Equivalent (IU) |
|---|---|
| 0.1 mg | 0.3 IU |
| 0.25 mg | 0.75 IU |
| 0.33 mg | 0.99 IU |
| 0.5 mg | 1.5 IU |
| 0.67 mg | 2.01 IU |
| 1 mg | 3 IU |
| 1.33 mg | 3.99 IU |
| 1.5 mg | 4.5 IU |
| 1.67 mg | 5.01 IU |
| 2 mg | 6 IU |
| 2.5 mg | 7.5 IU |
| 3 mg | 9 IU |
| 3.33 mg | 9.99 IU |
| 4 mg | 12 IU |
| 5 mg | 15 IU |
| 6 mg | 18 IU |
| 7 mg | 21 IU |
| 8 mg | 24 IU |
| 10 mg | 30 IU |
| 12 mg | 36 IU |
| 15 mg | 45 IU |
| 20 mg | 60 IU |
| 25 mg | 75 IU |
| 30 mg | 90 IU |
Vial sizes you actually see
Most somatropin vials are labelled in IU. Here is what each common vial size contains in milligrams of recombinant human growth hormone.
| Vial size (IU) | Equivalent (mg) |
|---|---|
| 4 IU | 1.33 mg |
| 6 IU | 2 mg |
| 10 IU | 3.33 mg |
| 12 IU | 4 mg |
| 15 IU | 5 mg |
| 16 IU | 5.33 mg |
| 24 IU | 8 mg |
| 30 IU | 10 mg |
| 36 IU | 12 mg |
| 45 IU | 15 mg |
Why 1 mg of somatropin = 3 IU
The International Unit (IU) measures biological activity rather than mass. For recombinant human growth hormone, the World Health Organization reference standard defines a fixed potency, and every FDA-approved somatropin product is calibrated against it. The conversion that comes out of that calibration is 1 mg = 3 IU.
In practical terms, that means a 10 IU vial of somatropin contains approximately 3.33 mg of growth hormone. A 6 IU vial contains 2 mg. A 36 IU vial contains 12 mg. The arithmetic is identical regardless of brand — Genotropin, Humatrope, Norditropin, Saizen, and Omnitrope all use the same 3 IU per mg ratio.
The reason vials are labelled in IU rather than mg is historical: protein-based hormones were first standardised by activity assay, before mass spectrometry made precise mass measurement routine. The IU convention persists because it is what every clinician, prescribing label, and reconstitution chart was originally built around. Some compounded somatropin products use mg labelling, in which case the same 3-to-1 conversion applies in reverse.
Frequently asked questions
- How many IU is 1 mg of somatropin?
- By the standard clinical convention, 1 mg of somatropin (recombinant human growth hormone) equals approximately 3 IU. The exact figure on FDA-approved labels is 3 IU per mg.
- Why is somatropin labelled in IU rather than mg?
- International Units measure biological activity rather than mass. Recombinant proteins like somatropin are dosed by activity because small structural variants can have different potencies at the same mass. The IU is calibrated against the WHO somatropin reference standard.
- Is the 3 IU per mg ratio the same for every somatropin brand?
- Yes. Genotropin, Humatrope, Norditropin, Saizen, Omnitrope, and other FDA-approved somatropin brands all use the 3 IU per mg conversion. Vial labels may use either unit depending on the brand and market.
- How many mg is 10 IU of somatropin?
- 10 IU divided by 3 IU per mg equals approximately 3.33 mg. A 10 IU vial of somatropin contains about 3.33 mg of recombinant human growth hormone.
- Does 1 mg always equal exactly 3 IU?
- The 3 IU per mg conversion is the standard reference value that every FDA-approved somatropin label uses. The actual measured biological activity per mg is calibrated against the WHO reference standard, and minor lot-to-lot variation is normal but converges to the labelled potency.
PeptideDose is an educational reference. It is not medical advice and does not replace consultation with a licensed healthcare provider. Doses shown in presets are derived from published protocols and product labels — they are not personal recommendations.