# Peptide Concentration Calculator

Concentration is the amount dissolved divided by the total liquid. Enter both to get mg/mL and mcg/mL, the amount in 0.1 mL and in one U-100 unit, and, if you want, the stock volume that makes a weaker solution.

Canonical: https://bestpeptidecalculator.app/concentration-calculator
Last reviewed: 2026-11-08

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

## The concentration formula

`concentration (per mL) = amount dissolved ÷ total liquid (mL)`

Because 1 mg is 1,000 mcg, a concentration in mg/mL times 1,000 is the same concentration in mcg/mL. A 10 mg vial in 2 mL is 5 mg/mL, or 5,000 mcg/mL.

| Volume | U-100 units | Amount |
| --- | --- | --- |
| 0.01 mL | 1 unit | 0.05 mg (50 mcg) |
| 0.05 mL | 5 units | 0.25 mg (250 mcg) |
| 0.1 mL | 10 units | 0.5 mg (500 mcg) |
| 1 mL | 100 units | 5 mg (5,000 mcg) |

## Diluting a solution (C1 × V1 = C2 × V2)

To make a weaker solution from a stronger one, the amount stays the same: concentration times volume before equals concentration times volume after.

`stock volume (V1) = weaker concentration (C2) × final volume (V2) ÷ stock concentration (C1)`

Example: from a 5 mg/mL stock, 3 mL at 1 mg/mL needs 1 × 3 ÷ 5 = 0.6 mL of stock, plus 2.4 mL of liquid. The calculator refuses a “weaker” concentration that is stronger than the stock.

## Concentration in IU

For a product labelled in IU, choose IU: the concentration comes out in IU/mL. IU measures biological activity, so it converts to mg only with that product’s own IU-per-mg factor. The calculator never assumes one. See [mg, mcg and IU explained](https://bestpeptidecalculator.app/guides/insulin-syringe-units-explained#iu).

## Frequently asked questions

### How do I work out mg/mL?

Divide the amount in mg by the volume in mL. 10 mg in 2 mL is 5 mg/mL.

### How many mcg are in 1 mL?

It depends entirely on the concentration: at 2.5 mg/mL, 1 mL holds 2,500 mcg; at 5 mg/mL it holds 5,000 mcg. mL is a volume and mcg is a mass, so you can’t convert one to the other without a concentration.

### Is 1000 mcg in 1 mL?

Only when the concentration is 1 mg/mL. 1,000 mcg is always 1 mg, but how much liquid holds it depends on the solution.

### What does diluting a solution do?

It lowers the concentration while keeping the amount the same, so each amount takes up more volume. Use C1 × V1 = C2 × V2 to find how much stock to use.

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