# Peptide Mixing Calculator

This calculator works backwards from the syringe. Enter the amount in the vial, the amount you want to measure, and the volume it should fill (for example 20 units). It tells you how much liquid to mix in, and lists other liquid volumes that also land exactly on a marking.

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

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

## The mixing formula

`liquid to add = chosen volume × amount in the vial ÷ amount you want to measure`

This is the reconstitution formula turned around. Instead of asking what volume an amount takes up, it asks how much liquid makes that amount take up the volume you picked.

Example: a 10 mg vial, 500 mcg to fill 20 units (0.2 mL). 0.2 mL × 10,000 mcg ÷ 500 mcg = 4 mL of liquid, which gives 2.5 mg/mL.

## Why pick the volume first

- A whole marking (10, 20 or 25 units) reads exactly. Values between markings don’t.
- Very small volumes magnify reading errors: one unit is 10% of a 10-unit volume, but 5% of a 20-unit one.
- Round liquid volumes (2, 2.5, 3, 4 mL) are easier to measure and to check by hand.

The calculator also shows the U-100 units your amount comes to, and warns when the volume is too small to measure or larger than the syringe.

## Liquid to add for a 20-unit volume

| Vial | Amount | Liquid to add | Concentration |
| --- | --- | --- | --- |
| 5 mg | 250 mcg | 4 mL | 1.25 mg/mL |
| 5 mg | 500 mcg | 2 mL | 2.5 mg/mL |
| 10 mg | 500 mcg | 4 mL | 2.5 mg/mL |
| 10 mg | 1,000 mcg | 2 mL | 5 mg/mL |

## Frequently asked questions

### How much bacteriostatic water should I mix with a peptide?

Any volume works mathematically; it only changes the concentration. Pick the volume you want your amount to fill and the calculator gives the liquid to add. See [how much bacteriostatic water to add](https://bestpeptidecalculator.app/guides/how-much-bac-water).

### Is a mixing calculator different from a reconstitution calculator?

It uses the same formula in the other direction. The [reconstitution calculator](https://bestpeptidecalculator.app/reconstitution-calculator) starts from the liquid you already added; the mixing calculator starts from the volume you want to measure.

### What if my vial is labelled in IU?

Choose IU for both the vial and your amount. Mixing IU with mg needs the product’s own IU-per-mg factor, which you enter yourself.

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