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mcg to mg Calculator — Convert Micrograms to Milligrams

Bidirectional live converter: type in either field and the other updates instantly. Includes a quick reference table for the most common peptide doses.

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1 mg = 1,000 mcg  |  1 mcg = 0.001 mg

— micrograms (mcg)
— milligrams (mg)

Common peptide doses — click to convert:

mcg to mg Quick Reference Table

Common peptide dose conversions from micrograms to milligrams, with typical use cases for each dose range.

Micrograms (mcg) Milligrams (mg) Typical Peptide Use
100 mcg 0.1 mg Ipamorelin, Hexarelin, GHRP-6
200 mcg 0.2 mg Sermorelin, Semax, Ipamorelin
250 mcg 0.25 mg BPC-157, Selank, DSIP
500 mcg 0.5 mg Semaglutide starting dose, PT-141
1,000 mcg 1 mg AOD-9604, GHK-Cu, PT-141 standard
2,000 mcg 2 mg TB-500, Tesamorelin, CJC-1295
2,400 mcg 2.4 mg Cagrilintide weekly dose
5,000 mcg 5 mg BPC-157 full vial, Epithalon, MOTS-C

Why mcg and mg Both Matter for Peptide Dosing

Peptide dosing involves two units that are easy to confuse: micrograms (mcg) and milligrams (mg). Vial sizes are almost always labeled in milligrams — a BPC-157 vial is "5 mg", a semaglutide vial is "5 mg", a tirzepatide vial is "10 mg". But dosing instructions and clinical literature typically express doses in micrograms — "250 mcg of BPC-157 twice daily", "500 mcg of semaglutide weekly to start".

The conversion is straightforward: 1 mg = 1,000 mcg. But when you are calculating injection volumes, preparing multiple vials, or scaling doses, it is easy to make a tenfold error by losing track of which unit you are working in. A dose of 250 mcg is 0.25 mg — if you accidentally treat it as 250 mg, the error is a factor of 1,000.

For GLP-1 agonists, the unit confusion can be especially consequential. Semaglutide doses ramp from 0.25 mg (250 mcg) to 2.4 mg (2,400 mcg) per week for weight management. Tirzepatide doses range from 2.5 mg (2,500 mcg) to 15 mg (15,000 mcg). Having a reliable converter on hand prevents costly mistakes at every step.

Bookmark this page and use it every time you switch between package labeling (mg) and dosing protocols (mcg). The bidirectional calculator above updates in real time — type either value and the other fills in immediately, eliminating any chance of arithmetic error.

Frequently Asked Questions

There are exactly 1,000 micrograms (mcg) in 1 milligram (mg). The "micro-" prefix means one-millionth (10⁻⁶) while "milli-" means one-thousandth (10⁻³) — so a microgram is one-thousandth of a milligram. This is the most fundamental conversion in peptide dosing: 1 mg = 1,000 mcg, 0.5 mg = 500 mcg, 0.25 mg = 250 mcg.
Divide the mcg value by 1,000. For example: 250 mcg ÷ 1,000 = 0.25 mg. To go the other direction (mg to mcg), multiply by 1,000: 0.25 mg × 1,000 = 250 mcg. The calculator above does this automatically in real time — type in either box and the other updates instantly.
2 mg = 2,000 mcg. This is a dose that comes up frequently: TB-500 is typically dosed at 2,000 mcg (2 mg) per injection twice weekly during a loading phase, tesamorelin is dosed at 2,000 mcg (2 mg) daily, and CJC-1295 is often used at 2,000 mcg (2 mg) per week.
50 mg = 50,000 mcg. Large-format peptide vials like GHK-Cu (50 mg) and SS-31 (50 mg) use this vial size, but individual doses from these vials are still measured in hundreds to thousands of mcg — for example, GHK-Cu is typically used at 1,000 mcg (1 mg) per injection, meaning a 50 mg vial provides 50 doses.
Yes — 500 mcg and 0.5 mg are identical quantities. 500 ÷ 1,000 = 0.5. This is a very common dose: the semaglutide maintenance starting dose is 0.5 mg (500 mcg) weekly, PT-141 is often started at 500 mcg (0.5 mg), and melanotan II is commonly used at 500 mcg (0.5 mg) per injection.
mg to ml Calculator Convert milligrams to milliliters for any concentration. BAC Water Calculator Calculate how much bacteriostatic water to add to any peptide vial. Reconstitution Calculator Full peptide reconstitution — concentration, volume, and doses per vial. Peptide Dosage Chart Standard dosing ranges for the most common research peptides.