Reference tool
Reconstitution calculator
Enter what is in the vial and what you are adding to it. The calculator returns the concentration, the volume to draw, and where that lands on a U-100 insulin syringe.
Calculator
How the arithmetic works
There are only two steps, and the calculator is doing nothing more than this.
concentration (mg/ml) = fill weight (mg) ÷ diluent volume (ml)
units on a U-100 syringe = (amount (mg) ÷ concentration (mg/ml)) × 100
The second step works because a U-100 syringe is graduated so 100 units is exactly 1 ml. One unit is therefore 0.01 ml, whatever is in the barrel.
Choosing the diluent volume is the only judgement call. A larger volume gives a lower concentration and a bigger draw, which is easier to measure accurately. A smaller volume concentrates the solution and makes small errors matter more. Aim for a draw between 10 and 50 units, which is the range where the graduations are easiest to read.
Questions
How do you calculate peptide reconstitution?
Divide the fill weight of the vial by the volume of diluent you add. A 10 mg vial with 2 ml of bacteriostatic water gives 5 mg/ml. To find the draw volume, divide the amount you want by that concentration. On a U-100 insulin syringe, multiply the volume in millilitres by 100 to get the unit marking.
What is the formula for units on an insulin syringe?
Units = (amount in mg ÷ concentration in mg per ml) × 100. A U-100 syringe is graduated so that 100 units equals exactly 1 ml, which means one unit is 0.01 ml regardless of what is in the barrel.
How much bacteriostatic water should be added to a vial?
There is no single correct volume. More diluent gives a lower concentration and a larger, easier-to-measure draw. Less gives a smaller draw but more measurement error. Most work lands between 1 ml and 3 ml per vial, chosen so the target draw falls between 10 and 50 units where the syringe is most readable.
Does the diluent volume change how much compound is in the vial?
No. The vial contains a fixed mass of lyophilised powder. Adding diluent only changes the concentration of the resulting solution and therefore the volume you draw. The total amount available is unchanged.
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