Peptide Calculator

How the math works

1. Concentration — vial mg ÷ water ml. A 10mg vial with 2ml of bacteriostatic water is 5 mg per ml.
2. Volume per dose — dose mg ÷ concentration. A 2mg dose at 5 mg/ml is 0.4 ml of solution.
3. Syringe units — on a U-100 insulin syringe, 1 ml = 100 units, so 0.4 ml means drawing to the 40-unit mark.

Quick reference — 10mg vial

Milligrams, micrograms, and units — the three vocabularies

Dosing discussions mix three unit systems, and most dosing errors are unit errors:

• mg ↔ mcg: 1 mg = 1,000 mcg. A 250 mcg dose is 0.25 mg; the calculator accepts either once you convert.
• Syringe units are volume, not dose: “40 units” means 0.4 ml on a U-100 syringe. How much compound that contains depends entirely on your concentration. That is why “how many units should I draw?” has no answer without knowing vial size and water added.
• U-100 vs U-40: the number is units per ml. The same 0.4 ml draw reads 40 units on a U-100 but 16 units on a U-40. Mixing them up is a 2.5x dosing error, which is why the calculator asks.

The math is only as good as the vial

This calculator assumes your 10mg vial holds 10mg. Published third-party testing shows label claims regularly miss in this market: in 2024, roughly 43% of research peptides submitted to Janoshik Analytical failed to meet their label claims. Check your vendor’s published batch results on their PeptideCensus profile before relying on the label.

Common questions

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

There is no single right answer. More water means lower concentration and larger, easier-to-measure draws. 2ml on a 10mg vial (5 mg/ml) is a common middle ground in research protocols; small doses of potent compounds measure more accurately at lower concentrations.

How many units is 5mg?

Impossible to answer without concentration; that’s the point of the calculator. At 5 mg/ml, a 5mg dose is 1 ml = 100 units on a U-100; at 10 mg/ml it’s 0.5 ml = 50 units.

Does the calculator work for any peptide?

Yes: the reconstitution math is identical for retatrutide, tirzepatide, BPC-157, TB-500, or anything else in a lyophilized vial. Compound-specific context lives on each peptide hub.

Can I use a regular syringe instead of an insulin syringe?

The math still works in ml, but insulin syringes exist because sub-1ml volumes need fine graduations; a 3ml syringe measuring a 0.15ml draw is guesswork.

How long does a reconstituted vial last?

With bacteriostatic water and refrigeration, research protocols commonly work within a several-week window, but stability varies by compound. Check the peptide’s hub page, and when in doubt, reconstitute smaller vials.

Does the math change if my vial is underdosed?

Yes, proportionally. A “10mg” vial that tested at 8mg makes every calculated dose 20% lighter than intended. That is why batch results matter more than arithmetic.