Best Answer: Insulin is standardized to 100 units per ml. So a ten ml bottle has 1000 units. So in your question take 100/15 = .15 ml. It will say the strength on the bottle. Insulin with a strength of 100 units per ml is cal U-100. There is also U-500 for diabetics with extreme insulin resistance, but it is very uncommon. If your insulin syringe is .3ml that is typical, 15 units is half a syringe.