Insulin Day Supply Calculator
Use this free insulin day supply calculator to work out how many days an insulin pen or vial will last.
Medical safety notice: This tool performs calculations only and does not establish a safe or appropriate treatment or dose. Verify all units and product instructions with a licensed clinician or pharmacist before acting on the result.
How the insulin day supply calculator works
Days = units in container ÷ (daily dose + priming units × injections per day). Opened insulin must be discarded after its labelled in-use period.
Frequently asked questions
Does priming matter?
Yes. Each priming dose uses units that do not reach you, so it shortens the supply.
Results are estimates for general information only. They are not a substitute for professional advice where applicable. Found a mistake? Report an error.