International Unit (IU)
Also known as: IU
An International Unit (IU) is a measure of biological activity rather than mass. For HGH, 1 IU is approximately equal to 333 mcg; most research peptides are dosed in mcg, not IU.
Overview
The International Unit was developed because different preparations of the same biological substance can vary in mass but have equivalent activity — the IU standardizes by activity rather than weight. HGH is the most common compound in the peptide research world dosed in IU. Converting between IU and mcg for HGH uses the factor 1 IU ≈ 333 mcg (or 3 IU ≈ 1 mg). Most synthetic research peptides — including GHRH analogues and GHRPs — are dosed in mcg, not IU, so the IU concept is primarily relevant when studying protocols involving exogenous HGH alongside these peptides. An IU conversion calculator can help when cross-referencing HGH literature.
Related Calculators
Frequently asked questions
How do I convert IU to mcg for HGH?+
Multiply IU by 333 to get mcg. For example, 2 IU of HGH = 666 mcg = 0.666 mg.
Do research peptides like BPC-157 or Ipamorelin use IU dosing?+
No. Research peptides like BPC-157 and Ipamorelin are dosed in micrograms (mcg), not IU. The IU unit is most relevant for HGH and a few other biologics.
Is the IU the same for all substances?+
No. The IU is substance-specific — 1 IU of HGH, 1 IU of vitamin D, and 1 IU of vitamin E all represent different masses because they are calibrated to the biological activity of each particular compound.