Reconstitution calculator
Tell it what is in the vial, how much water went in, and what you are aiming for. It gives you the mark to draw to — and, more importantly, it tells you when your dose does not land on one.
Your vial
Draw to
Lands exactly on a mark10units
0.100 mL · delivers 250 mcg
Concentration
2500
mcg / mL
Per unit
25.0
mcg / unit
Doses in the vial
20
~20 days
Why the syringe picker matters
Every insulin syringe is U-100: 100 units per millilitre, so one unit is 0.01 mL on all of them. The 1 mL, 0.5 mL and 0.3 mL labels are barrel capacities, not different scales. What actually changes is how finely the barrel is marked — a 1 mL barrel usually steps in 2 units, which is why small doses land between marks on it and read cleanly on a 0.3 mL.
The U-40 trap
U-40 syringes are veterinary and hold 40 units per millilitre. They look almost identical. If you draw to “20 units” on a U-40 barrel thinking it is U-100, you take 0.5 mL instead of 0.2 mL — two and a half times your intended dose. This calculator will shout at you if you pick one.