Semaglutide reconstitution calculator
Compounded semaglutide arrives as a vial rather than a pre-filled pen, so the draw has to be calculated rather than dialled. This calculator turns your vial amount, the bacteriostatic water you add, and the dose you have decided on into an exact draw on a labelled syringe. It does not tell you what dose to take, and it is not a substitute for the instructions from the clinician who prescribed it.
mL
Error: Enter the amount in the vial.
Error: Enter how much water you are adding.
Error: Enter your dose.
Your draw appears here as you type.
Math only. You set the dose. Not medical advice. Double-check before you inject.
How to calculate a Semaglutide draw
- How do I calculate a semaglutide draw?
- Two steps. First, concentration equals the amount in the vial divided by the volume of bacteriostatic water you added. Second, draw volume equals your dose divided by that concentration. Here is the arithmetic on stand-in numbers, which are an illustration of the method and not advice about what to use: if a vial holds 5 mg and you add 2 mL of water, the concentration is 2.5 mg per mL, so drawing one tenth of the vial means 0.2 mL, which reads as 20 units on a U-100 syringe. Put your own semaglutide vial amount, your own water volume, and your own dose into the calculator above and it does this exactly, in decimal arithmetic, and shows the draw on a labelled syringe.
- How much bacteriostatic water should I add to a semaglutide vial?
- That is your decision, not ours, and there is no single right answer: more water gives a larger, easier-to-measure draw, less water gives a smaller one. Use Plan mode: enter the vial amount, the dose you have decided on, and the draw size you find comfortable to read on your syringe, and the calculator solves for the volume of bacteriostatic water that produces it.
- How many units is my draw on an insulin syringe?
- On a U-100 insulin syringe, 100 units equal 1 mL, so one unit is 0.01 mL. Multiply your draw volume in mL by 100 to get units. A U-40 syringe is a different scale: 40 units equal 1 mL, so the same liquid reads 2.5 times fewer units. The calculator labels the syringe it is drawing so the scale is never ambiguous.
- What is the difference between mg and mcg for semaglutide?
- 1 mg equals 1000 mcg. This is the single most dangerous confusion in reconstitution, because entering a number in milligrams when you meant micrograms is a 1000-fold error. The calculator blocks any dose larger than the entire vial and offers to reinterpret your number in the other unit, but it never changes your entry for you.
- How many doses are in a semaglutide vial?
- Divide the total amount in the vial by the size of one dose. The water you add does not change this number: water changes the concentration and therefore the volume you draw, but not how much compound is in the vial.
- Why does my syringe read a different number of units than I expected?
- On a U-100 insulin syringe, 100 units equal 1 mL, so one unit is 0.01 mL. Multiply your draw volume in mL by 100 to get units. A U-40 syringe is a different scale: 40 units equal 1 mL, so the same liquid reads 2.5 times fewer units. The calculator labels the syringe it is drawing so the scale is never ambiguous.