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Days' supply calculator
Days' supply is the quantity dispensed divided by the quantity used each day (amount per dose times doses per day), rounded down to whole days. Enter the numbers as written on the prescription and the calculator returns the days' supply, any leftover quantity, and the last day the fill covers.
Check days' supply on your whole fill report, free · Free to start. No card.
How it's calculated
Quantity per day = amount per dose x doses per day. Days' supply = quantity dispensed / quantity per day, rounded down. The fill date counts as day 1. The tool does arithmetic on the numbers you enter. It does not check a dose, a drug, or a plan's day limits.
Questions
How do you calculate days' supply?
Divide the quantity dispensed by the quantity taken per day. 90 tablets at 1 tablet 3 times a day is 90 / 3 = 30 days.
Why does days' supply round down?
A claim reports whole days. 100 tablets at 3 a day is 33.3 days, reported as 33, with 1 tablet left over.
How does days' supply affect PDC?
PDC counts the days a patient had medication on hand, using the days' supply on each fill. A wrong days' supply moves the PDC and the fail date.