# Peptide Unit Converter

Every peptide unit conversion that doesn’t need a concentration, in one place: amounts (mg, mcg, IU), concentrations (mg/mL, mcg/mL) and syringe volumes (mL, U-100 units, U-40 units). Conversions between mass and volume need a concentration and are on the [mcg to mL calculator](https://bestpeptidecalculator.app/mcg-to-ml-calculator).

Canonical: https://bestpeptidecalculator.app/unit-converter
Last reviewed: 2026-11-08

Interactive calculator on the page: units, convert. It runs in the browser and never suggests an amount.

## Which units convert directly

| From → to | Converts directly? | How |
| --- | --- | --- |
| mg ↔ mcg | Yes | 1 mg = 1,000 mcg |
| mg/mL ↔ mcg/mL | Yes | × or ÷ 1,000 |
| mL ↔ U-100 units | Yes | 1 mL = 100 units |
| mL ↔ U-40 units | Yes | 1 mL = 40 units |
| IU ↔ mg | Only with a factor | IU = mg × the substance’s IU per mg |
| mcg ↔ mL | No | Needs the concentration: [mcg to mL calculator](https://bestpeptidecalculator.app/mcg-to-ml-calculator) |

## Why IU needs a factor

An international unit measures biological activity against a reference standard, so each substance has its own number of IU per mg. The converter only converts IU when you enter that factor from the product’s label or data sheet; it never assumes one.

## Frequently asked questions

### What is a peptide unit calculator?

A converter for the units peptide math uses: mass (mg, mcg), activity (IU, with a factor), concentration and syringe volume.

### How many mcg in a mg?

1,000. See the [mg to mcg calculator](https://bestpeptidecalculator.app/mg-to-mcg-calculator) for a full table.

### How many units is 1 mL?

100 units on a U-100 syringe and 40 on a U-40 syringe.

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Research and educational use only. Not medical advice. Best Peptide Calculator is powered by Peptide Library (https://peptidelibrary.app).