Micrograms ↔ Milligrams

mcg
mg
Conversion1 mg = 1000 mcg

Millilitres ↔ Insulin units (U-100)

mL
u
Conversion1 mL = 100 u · 1 u = 0.01 mL

Micrograms ↔ Insulin units (by concentration)

mg
Total peptide in the vial.
mL
Diluent added to the vial.
mcg
u
Concentration2.5 mg/mL
Per unit on syringe25 mcg/unit

International units ↔ Milligrams

IU/mg
IU measures activity, not mass — this factor is substance-specific and you must supply the correct one for your peptide (e.g. HGH is commonly quoted at ~3 IU per mg).
IU
mg
Using factor3 IU/mg · 0.3333 mg/IU

How this works

Methodology reviewed July 2026

Four small, bidirectional converters handle the units that trip people up. Mass is a fixed ratio — 1 mg is 1000 mcg. Volume on a U-100 insulin syringe is another fixed ratio — 1 mL is 100 units, so 1 unit is 0.01 mL — and depends only on the liquid volume, not what's dissolved in it. Converting a dose in micrograms to units, though, needs a concentration, so that card derives mg/mL from the vial strength and water you enter and turns it into micrograms per unit. International Units measure biological activity rather than mass, so IU-to-mg requires a substance-specific IU-per-mg factor you supply. Type in either box of any card and its partner updates instantly.

Formula# Card 1 — mass mcg = mg × 1000 mg = mcg / 1000 # Card 2 — volume (U-100) units = mL × 100 mL = units / 100 # Card 3 — dose ↔ units by concentration concentration [mg/mL] = vial_strength_mg / bac_water_mL mcg_per_unit = concentration × 1000 / 100 (= vial_mg × 10 / bac_mL) units = dose_mcg / mcg_per_unit dose_mcg = units × mcg_per_unit # Card 4 — activity ↔ mass (substance-specific factor f = IU per mg) mg = IU / f IU = mg × f
Inputs

Micrograms / milligrams · Millilitres / insulin units · Vial strength (mg) + water (mL) + dose · IU-per-mg factor

Outputs

Converted mass · Converted volume · Concentration (mg/mL) and mcg per unit · IU/mg and mg/IU

Assumptions
  • Insulin-unit conversions assume a standard U-100 syringe (100 units = 1 mL).
  • The mL-to-units conversion is purely volumetric and does not depend on the dissolved peptide.
  • The dose-by-concentration card assumes a uniform, fully dissolved solution at the concentration you derive from vial strength and water.
  • The IU-per-mg factor is substance-specific and must be supplied correctly for your peptide (e.g. hGH is commonly quoted near 3 IU per mg); a wrong factor makes the IU conversion wrong.
Limitations
  • These are plain unit conversions on the numbers you enter; they do not evaluate whether any dose is safe or appropriate.
  • IU has no universal mass equivalent — the same IU maps to different masses for different substances — so an incorrect or borrowed factor silently produces a wrong answer.
  • The tool cannot verify that a vial's stated strength or a syringe's calibration is accurate.
Safety
  • The whole tool exists because micrograms, milligrams, millilitres, insulin units, and IU are five distinct quantities; convert deliberately and never treat a unit swap as interchangeable by name.
  • Every output is an arithmetic conversion of your inputs, not a recommended or safe dose for anyone.
  • Impossible inputs are guarded — non-positive vial strength or water blocks the concentration card, and a non-positive IU-per-mg factor blocks the IU card, with a message rather than a misleading number.
  • Because IU is activity-based, always confirm the correct IU-per-mg factor for your exact substance before trusting an IU conversion.

This calculator is for educational purposes only and is not medical advice, diagnosis, or treatment. Results are estimates based on published formulas and population averages — your individual values may differ. Nothing here is calculated on a server: everything runs in your browser and no data is stored or sent anywhere. Always consult a qualified clinician before making health, medication, or training decisions.