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Peptide Unit Converter (IU ↔ mcg ↔ mg)
Convert between micrograms (mcg), milligrams (mg), and International Units (IU) with custom conversion ratios.
01Inputs
02The answer
Converted Value
0.5mg
Converted from 500 mcgEquivalent in mg
0.500mg
Standard mass unit
Equivalent in mcg
500mcg
Micrograms
03How this works
Dosage Unit Conversion Standards
Written out so you can check it by hand. The app runs this exact function, not a second implementation that drifts.
Understanding mass and biological activity units avoids dosing confusion across different compound labels.
1. Micrograms & Milligrams: Metric mass units related by a factor of 1,000.1 mg = 1,000 mcg and 1 mcg = 0.001 mg.
2. International Units (IU): IU measures biological potency. When converting IU to mass, Mass (mg) = IU ÷ (IU/mg Factor).
04Questions
- How do I convert micrograms (mcg) to milligrams (mg)?
- To convert mcg to mg, divide by 1,000. Example: 250 mcg ÷ 1,000 = 0.25 mg. Conversely, multiply mg by 1,000 to convert to mcg.
- What is an International Unit (IU)?
- An International Unit (IU) measures biological activity rather than physical mass. Because activity per mg differs by compound, an IU-to-mass conversion needs a compound-specific factor: somatropin, for example, is standardized at 3 IU per mg (WHO International Standard 98/574). Check your compound's label or certificate of analysis for its factor.
- How do I convert a dose in mcg to insulin-syringe units?
- Units on a U-100 insulin syringe measure volume, not mass: 100 units equal 1 ml. The conversion therefore depends on your vial's concentration: divide the dose in mg by the concentration in mg/ml to get the draw volume in ml, then multiply by 100 for units. The reconstitution calculator runs this for you and draws the barrel.
- What is the most common IU conversion mistake?
- Reusing one compound's IU factor for another. An IU is defined per compound (3 IU of somatropin and 3 IU of hCG describe unrelated quantities of unrelated molecules), so a factor carried over from a different compound produces a number that is precisely wrong. The second mistake is treating IU as a unit of mass; it measures biological activity.
- Why do peptides use both mcg and mg units?
- Potent compounds (like BPC-157 or Semax) are dosed in microgram quantities (mcg) to prevent overdose errors, whereas larger compounds or vial contents are measured in milligrams (mg).
05Related calculators
ReconstitutionVial size and BAC water in, concentration and syringe units out, with a visual fill indicator.Half-lifeHow much of a compound remains after a given interval, and when it settles at steady state.Vial longevityHow long a reconstituted vial lasts at your schedule, and when to order the next one.Cost per doseVial price against doses per vial, so suppliers compare on the number that matters.GLP-1 titrationLay a titration schedule against real dates and see the whole ramp at once.
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