Peptide tools

Peptide reconstitution calculator

Peptides are prescribed in micrograms and drawn on a syringe marked in units, and nothing on the vial or the syringe converts between the two. The conversion also changes every time you use a different amount of water. This does that arithmetic and shows its working.

Peptide in the vial

Printed on the vial, e.g. 5 mg

Bacteriostatic water added

What you are reconstituting with

Dose you were prescribed

mcg

Micrograms, not milligrams

Draw to this mark

10 units

on a 1 mL U-100 insulin syringe — that is 0.100 mL

Concentration: 2,500 mcg/mL; 2.50 mg/mL
Volume per dose: 0.100 mL; Before any dead space in the needle
Doses in the vial: 20; Exact

Why this is the step that goes wrong

A vial holds a fixed quantity of dry peptide. Adding 1 mL of water or adding 3 mL does not change how much peptide is in there — it changes how concentrated each milliliter is, and therefore how far up the syringe a single dose reaches. Two people with identical vials and identical prescriptions will draw to different marks if they used different amounts of water.

That is why a units figure copied from somebody else, or from a video, is not transferable. It is only correct for the concentration it was worked out at.

What this calculator is not

It is arithmetic, not advice. It does not know what dose you should be taking, and it will convert any number you type without judging it. The dose belongs to whoever prescribed it.

It also says nothing about whether a given peptide should be bought at all. Several sold online are not approved for any use and are not eligible for compounding by a licensed US pharmacy, which means what arrives has no one standing behind its identity, purity or strength. Our peptide status checker gives the regulatory and evidence standing of each one we cover, and the peptide register sets out what is actually known about each.

After you reconstitute

Bacteriostatic water contains benzyl alcohol as a preservative, and its own monograph gives a 28-day in-use expiry once the vial has been punctured. That clock starts at first puncture, not at first dose. Our beyond-use date tracker works the dates out, and the vial label reader covers what the printing on a compounded vial is telling you.

References

1.United States Pharmacopeia. USP <797> Pharmaceutical Compounding — Sterile Preparations (2023 revision; beyond-use dating for compounded sterile preparations). USP General Chapters. 2023. https://www.usp.org/compounding/general-chapter-797
2.Hospira / Pfizer. Bacteriostatic Water for Injection, USP — Multi-dose vial monograph (0.9% benzyl alcohol; 28-day in-use expiry after first puncture). FDA DailyMed. 2024. https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=87d6e9dc-fe3b-4593-ac9a-d7493d1959c7

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