mg vs mcg: Converting Peptide Amounts
One milligram equals 1000 micrograms, so mg → mcg multiplies by 1000 and mcg → mg divides by 1000.
Published · Updated · PepCalcs editorial team · Editorial policy
The conversion
Vials are usually labelled in mg, while research amounts for smaller peptides are frequently written in mcg. Mixing the two without converting produces an answer that is off by a factor of 1000 — by far the most common arithmetic error in reconstitution.
mcg = mg × 1000
mg = mcg ÷ 1000
Quick reference
- 0.25 mg = 250 mcg
- 0.5 mg = 500 mcg
- 1 mg = 1000 mcg
- 2.5 mg = 2500 mcg
- 5 mg = 5000 mcg
Why the calculator asks for the unit
PepCalcs asks you to pick mg or mcg explicitly rather than guessing from the size of the number. A value of 500 is a plausible mcg amount and an implausible mg amount, but the calculator will not silently reinterpret what you typed — it converts exactly what you selected.