Peptide Reconstitution Calculator: BAC Water to mcg & Units

Common vial setups

Starting points for the arithmetic, not protocols. Selecting a row fills the calculator.

Setup	Concentration
5 mg vial, 2 mL water, 250 mcg draw	2,500 mcg/mL
10 mg vial, 2 mL water, 500 mcg draw	5,000 mcg/mL
5 mg vial, 3 mL water, 250 mcg draw	1,667 mcg/mL
10 mg vial, 1 mL water, 1000 mcg draw	10,000 mcg/mL

How the numbers are derived

Concentration (mcg/mL) = vial mass (mg) x 1000 / diluent (mL). Draw (mL) = dose (mcg) / concentration. Units = draw (mL) x 100 on a U-100 syringe, regardless of syringe size; the syringe size only sets the maximum single draw. Doses per vial = vial mass (mcg) / dose (mcg), rounded down.

If net peptide content is entered, the vial mass is multiplied by that percentage first, so every downstream figure reflects actual peptide rather than gross lyophilized mass.

Questions

How do you calculate peptide concentration after reconstitution?

Concentration is vial mass divided by diluent volume. A 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.5 mg/mL, which is 2,500 mcg/mL.

How many units on an insulin syringe is a given dose?

Draw volume in mL is dose divided by concentration. On a U-100 syringe, 1 mL equals 100 units, so 0.1 mL is 10 units. A 250 mcg dose from a 2,500 mcg/mL solution is 0.1 mL, or 10 units.

How much bacteriostatic water should I add?

Any amount works arithmetically. More water gives a more dilute solution and a larger, easier to read draw for the same dose. Standard research vials hold about 3 mL, so volumes above that need a larger vessel.

Does the calculator account for net peptide content?

No. Lyophilized vials contain water and counterions, so the true peptide mass is the labelled mass multiplied by the net peptide content on the batch certificate of analysis. Apply that correction to the vial mass for exact quantitative work.

Storage, degradation and stability are covered in the reconstitution and storage guide.