# Peptide Reconstitution Calculator — units to draw & doses

Source: https://pepvault.app/tools/reconstitution-calculator

Last updated: 2026-09-29

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# Peptide reconstitution calculator

Work out exactly how many units to draw, the concentration, and how many doses you'll get per vial — and the best water amount to land your dose on a clean syringe mark.

[Try the 3D Reconstitution Lab](https://pepvault.app/lab)

Your vial and dose

Example numbers

Draw to 40 units on a U-100 syringe. Lands on a numbered mark. Concentration 5 mg per mL, 5 doses per vial.

Draw to

40 units on a U-100 syringe

Lands on a numbered mark

0.5 mL insulin syringe · 50 units

- **Concentration:** 5 mg/mL 5,000 mcg/mL
- **Doses per vial:** 5

## How reconstitution math works

Reconstitution is mixing a lyophilized (freeze-dried) peptide with bacteriostatic water so you can draw an accurate dose. The units you draw follow one formula: **units = dose (mcg) × water (mL) ÷ (vial mg × 10)**.

A useful thing to know: **the amount of water doesn't change how many doses are in the vial** — it only changes the concentration, i.e. how many units you draw for the same dose. More water means a larger, easier-to-read draw on the syringe.

Example: a 10 mg vial mixed with 2 mL of bacteriostatic water is 5 mg/mL, so a 2 mg dose is 40 units on a U-100 syringe, and the vial holds 5 doses.

## Reconstitution math: common questions

Worked arithmetic for reference, not a dose recommendation.

### How much bacteriostatic water should I add to a 10 mg vial?

The water sets the concentration, not how much peptide is in the vial. A 10 mg vial holds 10,000 mcg: with 1 mL of water that's 10,000 mcg/mL (100 mcg per unit on a U-100 syringe), with 2 mL it's 5,000 mcg/mL (50 mcg per unit), and with 3 mL it's about 3,333 mcg/mL (about 33 mcg per unit). A practical way to choose is the volume that puts the dose you're tracking on an easy-to-read syringe mark. Enter your vial, water and dose above and the calculator suggests one.

### How many units is 250 mcg from a 5 mg vial mixed with 2 mL of water?

10 units. 5 mg is 5,000 mcg, so 2 mL of water makes 2,500 mcg/mL, which is 25 mcg per unit on a U-100 syringe, and 250 mcg ÷ 25 mcg per unit = 10 units. The general formula is units = dose (mcg) × water (mL) ÷ (vial mg × 10).

### How do I work out the concentration of a reconstituted vial?

Concentration (mcg/mL) = vial mg × 1,000 ÷ water mL. A 5 mg vial with 2 mL of water is 2,500 mcg/mL; the same vial with 2.5 mL is 2,000 mcg/mL. Because 100 units on a U-100 insulin syringe equal 1 mL, each unit holds the concentration ÷ 100, so 25 mcg per unit at 2,500 mcg/mL.

### Does adding more water change how many doses are in a vial?

No. Doses per vial = vial mcg ÷ dose mcg, whatever the water volume. A 10 mg vial holds forty 250 mcg doses whether you add 1 mL or 3 mL. More water only makes each dose a larger draw, which is easier to read on the syringe.

### What is a unit on an insulin syringe?

On a U-100 insulin syringe, 100 units equal 1 mL, so 1 unit is 0.01 mL. Units measure volume, not dose: how much peptide each unit holds depends on how the vial was reconstituted.

## Used most with

- [Semaglutide](https://pepvault.app/peptides/semaglutide)
- [Tirzepatide](https://pepvault.app/peptides/tirzepatide)
- [Retatrutide](https://pepvault.app/peptides/retatrutide)
- [BPC-157](https://pepvault.app/peptides/bpc-157)
- [TB-500](https://pepvault.app/peptides/tb-500)
- [GHK-Cu](https://pepvault.app/peptides/ghk-cu)
- [Ipamorelin](https://pepvault.app/peptides/ipamorelin)
- [CJC-1295 no DAC](https://pepvault.app/peptides/cjc-1295-no-dac)

PepVault for iPhone

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## More free tools

- [Reverse reconstitution](https://pepvault.app/tools/reverse-reconstitution-calculator)
- [Half-life & active level](https://pepvault.app/tools/peptide-half-life-calculator)
- [GLP-1 titration planner](https://pepvault.app/tools/glp1-titration-calculator)
- [Dose & unit converter](https://pepvault.app/tools/peptide-dosage-calculator)
- [How long will my vial last?](https://pepvault.app/tools/how-long-will-my-vial-last)
- [Missed a GLP-1 dose?](https://pepvault.app/tools/missed-glp1-dose)
- [Is my mixed vial still good?](https://pepvault.app/tools/reconstituted-peptide-expiry)
- [Protein on a GLP-1](https://pepvault.app/tools/glp1-protein-calculator)
- [GLP-1 weight loss by week](https://pepvault.app/tools/glp1-weight-loss-by-week)
- [Peptide reference library](https://pepvault.app/peptides)

Choosing a tracker app? [Compare peptide tracker apps](https://pepvault.app/best-peptide-tracker-apps) · [Track what’s left in your vials](https://pepvault.app/peptide-vial-tracker-app)

PepVault is a research and tracking resource, not medical advice. Ranges are what studies used, never a dose for you. Brand names are trademarks of their owners; PepVault is independent of them.

For educational and tracking purposes only — not medical advice. Always verify calculations and consult a qualified clinician before changing any protocol.

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