Peptide unit converter
Convert a mass between grams (g), milligrams (mg), micrograms (mcg, µg), and nanograms (ng). An optional section converts micrograms to International Units (IU) only when a substance-specific factor is entered. All math runs in the browser.
Formula
Every unit is first converted to micrograms, then to the target unit: 1 g = 1,000,000 mcg; 1 mg = 1,000 mcg; 1 ng = 0.001 mcg. Result = value × (mcg per source unit) ÷ (mcg per target unit).
For IU: IU = mcg ÷ (mcg per IU). The factor must come from an official reference standard, label, or monograph for the specific substance.
Worked example
Example only: 2.5 mg × 1,000 = 2,500 mcg. Converting 2,500 ng to micrograms gives 2,500 × 0.001 = 2.5 mcg. If a hypothetical factor of 0.5 mcg per IU is entered, 10 mcg corresponds to 10 ÷ 0.5 = 20 IU.
Why IU is different
Grams, milligrams, micrograms, and nanograms are units of mass. An International Unit is a unit of biological activity defined against a reference preparation. Two substances with the same mass can have very different IU values, and the factor for one substance cannot be reused for another. That is why this tool never converts mass to IU without an explicit factor.
Limitations
- The tool performs arithmetic only and contains no substance data.
- Floating-point arithmetic can introduce rounding at extreme magnitudes; very large or small results are shown in scientific notation.
- Negative values are rejected.
Frequently asked questions
How many micrograms are in a milligram?
One milligram (mg) equals 1,000 micrograms (mcg or µg). One gram equals 1,000 milligrams, and one microgram equals 1,000 nanograms. Converting between these mass units is a fixed multiplication by powers of ten.
Why can't mg be converted to IU without more information?
An International Unit (IU) measures biological activity, not mass. The number of micrograms per IU is defined separately for each substance, and sometimes for each reference standard. Without that substance-specific factor, no generic conversion exists.
Where does a substance-specific IU factor come from?
Factors are defined by international reference standards or stated on official product labels and pharmacopoeia monographs. This tool does not supply factors; it only performs the arithmetic once a factor has been entered.
Does this tool suggest an amount of any substance?
No. It converts numbers between units. It contains no substance data and makes no suggestion about any amount, use, or administration.