Human Growth Hormone (HGH), also known as somatropin, is dosed in International Units (IU) rather than milligrams. This creates a conversion step that does not exist with most other peptides. Understanding the IU system is essential for accurate somatropin dosage calculation.
The IU to MG Conversion
For pharmaceutical-grade somatropin, the standard conversion is:
This means:
- 1 IU = 0.33mg
- 2 IU = 0.67mg
- 4 IU = 1.33mg
- 10 IU = 3.33mg
Some older or generic sources list 1mg = 2.7 IU. The 1:3 ratio is the current pharmaceutical standard used by brands like Norditropin, Genotropin, and Humatrope.
Common HGH Brands and Their Formats
Norditropin (Novo Nordisk)
Pre-filled pens available in:
- 5mg/1.5mL (15 IU per pen)
- 10mg/1.5mL (30 IU per pen)
- 15mg/1.5mL (45 IU per pen)
The pens have built-in dose selectors measured in mg. No reconstitution needed.
Genotropin (Pfizer)
Available as a two-chamber cartridge that mixes upon activation:
- 5mg (15 IU) and 12mg (36 IU) cartridges
- Also available in 0.2mg MiniQuick single-dose syringes
Generic HGH (Lyophilized Powder)
Typically sold as powder in vials requiring reconstitution:
- Common sizes: 10 IU (3.33mg), 12 IU (4mg), 24 IU (8mg) per vial
- Reconstitute with bacteriostatic water
- Calculate concentration based on water volume added
Calculating Generic HGH Doses
For a 10 IU vial reconstituted with 1mL of bacteriostatic water:
- Concentration = 10 IU per mL
- Per syringe unit = 0.1 IU
- For a 2 IU dose = 20 units on the syringe
- For a 4 IU dose = 40 units on the syringe
The formula is the same as other peptides, just using IU instead of mcg:
Typical Dosing Ranges
| Purpose | Daily Dose | Timing |
|---|---|---|
| Anti-aging / general wellness | 1-2 IU | Morning, before breakfast |
| Body composition / recovery | 2-4 IU | Split AM/PM or morning only |
| Clinical growth hormone deficiency | Per physician protocol | As prescribed |
Higher doses are sometimes split into two daily injections to better mimic the body natural pulsatile GH release pattern.
Somatropin vs. Secretagogues
Direct somatropin is exogenous growth hormone — you are injecting the hormone itself. Growth hormone secretagogues like Ipamorelin and CJC-1295 stimulate your pituitary to produce its own GH. They work through completely different mechanisms and are dosed in mcg, not IU.
If you are using secretagogues instead, see our Ipamorelin calculator or CJC-1295 calculator.
For exact dose-to-syringe-unit calculations for your specific HGH vial, use our HGH dosage calculator.