Free Tool

Peptide Reconstitution Calculator

Enter your vial strength and diluent volume to get concentration, exact syringe units per dose and how many doses the vial holds.

Inputs

Both are U-100: 1 unit = 0.01 mL.

Fill in the vial strength, bacteriostatic water and your desired dose above to see the concentration, syringe units and doses per vial.

Visual Syringe Guide

Fill in vial strength, bacteriostatic water and your desired dose above to see the syringe fill mark.

mg ↔ mcg Converter

1 mg = 1,000 mcg. Edit either field and the other updates instantly.

How the reconstitution math works

A lyophilised peptide vial lists its total contents in milligrams. When you add bacteriostatic water, you create a solution whose concentration is simply the vial contents divided by the water volume: a 5 mg vial with 2 mL of water gives 2.5 mg/mL (2,500 mcg/mL).

To find a dose volume, divide the desired dose by that concentration. At 2.5 mg/mL, a 250 mcg dose is 0.1 mL. On a U-100 insulin syringe — 100 units per 1 mL — that is exactly 10 units. This calculator performs each step for you and also divides the total vial contents by your dose to show how many doses one vial contains.

Worked examples

  • 10 mg vial + 2 mL water → 5 mg/mL. A 500 mcg dose = 0.1 mL = 10 units on a U-100 syringe; the vial holds 20 doses.
  • 5 mg vial + 1 mL water → 5 mg/mL. A 250 mcg dose = 0.05 mL = 5 units; the vial holds 20 doses.
  • 2 mg vial + 2 mL water → 1 mg/mL. A 100 mcg dose = 0.1 mL = 10 units; the vial holds 20 doses.

Common questions

Why bacteriostatic water instead of sterile water?

Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth so a multi-dose vial stays usable after repeated punctures. Plain sterile water for injection has no preservative.

What do 'units' on an insulin syringe mean?

Units are volume marks. On a U-100 syringe, 100 units equal 1 mL, so 10 units is 0.1 mL. The syringe does not know your concentration — the unit mark only becomes a dose once you know the mg/mL of your solution.

How do I convert mg to mcg?

Multiply milligrams by 1,000. 5 mg = 5,000 mcg. The converter above does this instantly in both directions.

Should I shake the vial to mix it?

No. Add water slowly down the vial wall and swirl gently until fully dissolved. Shaking can damage fragile peptide structures.

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Educational and research information only. This calculator performs arithmetic; it is not medical advice, dosing guidance or a recommendation to use any compound. Consult a licensed healthcare professional before any health decision.