Peptide Dosing Math: mg, mcg & IU Conversion

The single biggest source of peptide dosing errors is unit confusion — reading "250 mcg" and drawing the equivalent of 2500 mcg because someone mixed milligrams and micrograms. The math is simple once you see it; this guide exists so you don't have to reinvent it every time.

The four units

• mg — milligram. 1000 mcg.
• mcg — microgram. 1/1000th of a mg. Most peptide doses live here.
• IU — international unit. Used for some compounds (HGH, insulin). Not the same as syringe units.
• syringe units — markings on an insulin syringe. 100 syringe units = 1 mL. Do not confuse with IU.

The reconstitution step

You always start with two numbers:

• Peptide mass in mg (printed on the vial)
• BAC water volume in mL (chosen by you)

Dividing gives you concentration in mg/mL. Multiply by 1000 for mcg/mL.

The dosing step

You have three numbers to connect:

• Target dose (typically in mcg)
• Concentration (mcg/mL, from above)
• Volume to draw (mL, which converts to syringe units)

Volume in mL = target dose ÷ concentration.

Multiply by 100 to get syringe units (since 1 mL = 100 units on a standard insulin syringe).

Worked examples

Example 1 — Ipamorelin 200 mcg dose

• Vial: 5 mg lyophilized