How to convert mcg and mg
A milligram is 1,000 times larger than a microgram. To go from mg to mcg, multiply by 1,000; to go from mcg to mg, divide by 1,000. So 0.25 mg is 250 mcg, and 2,500 mcg is 2.5 mg.
This matters because peptide protocols mix the two units freely — recovery and growth peptides are usually written in mcg, while GLP-1 compounds are written in mg. Reading a dose in the wrong unit is how a 10× error happens, so it is worth converting deliberately.
Common peptide doses in both units
| Example | Micrograms | Milligrams |
|---|---|---|
| BPC-157 / TB-500 (recovery) | 250 mcg | 0.25 mg |
| Ipamorelin / CJC-1295 (growth) | 200 mcg | 0.2 mg |
| Semaglutide (starting) | 250 mcg | 0.25 mg |
| Tirzepatide (starting) | 2,500 mcg | 2.5 mg |
| Retatrutide (example) | 2,000 mcg | 2 mg |
Educational reference only. Not medical advice — follow the instructions from your clinician or pharmacy.
From a dose to syringe units
Converting mcg to mg is only the first step. To work out how much to draw on a syringe, you also need your vial strength and bacteriostatic water volume. Use a peptide reconstitution calculator for that full conversion, or a peptide-specific calculator below.