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.
Frequently asked questions
How many mcg are in a mg?
There are 1,000 micrograms (mcg) in 1 milligram (mg). To convert mg to mcg, multiply by 1,000; to convert mcg to mg, divide by 1,000.
Why do peptide doses mix mcg and mg?
Smaller doses (a few hundred micrograms, like many BPC-157 or ipamorelin doses) are easier to read in mcg, while larger doses (like GLP-1 compounds) are usually written in mg. The conversion is always ×1,000, but mixing the two units is a common source of 10× dosing errors.
Is mcg the same as µg or mcg?
Yes. 'mcg' and 'µg' both mean micrograms and are interchangeable. 'mcg' is preferred on labels because the µ symbol can be misread.
How do I turn a dose into syringe units?
Converting mcg to mg is only the first step. To get syringe units you also need your vial strength and bacteriostatic water volume — use a peptide reconstitution calculator for that full conversion.