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Working with the numbers
Units: mg, mcg, mL and IU
The unit mix-ups behind most calculation mistakes.
- mg (milligram) and mcg (microgram, sometimes written µg) measure mass. 1 mg = 1,000 mcg. Confusing them is a thousand-fold error.
- mL (millilitre) measures volume. How much peptide is in a mL depends entirely on how much water you added.
- IU (international units) measure biological activity, used for things like HGH and HCG. IU can't be converted to mg without product-specific information.
- Syringe units on a U-100 insulin syringe are volume: 100 units = 1 mL.
When something looks off by a factor of 10, 100 or 1,000, check the units first.
Key points
- 1 mg = 1,000 mcg.
- mL is volume, not amount of peptide.
- IU is activity and needs product-specific conversion.
Quick check
How many mcg are in 2.5 mg?
Multiply mg by 1,000: 2.5 × 1,000 = 2,500 mcg.
Can you convert 10 IU to mg without more information?
IU measure activity, and the mg per IU differs between products.
Sources
General education, not medical advice. Nothing here recommends using any compound or amount.