Days supply calculator
Enter how many pills you have and how you take them to see how many days they last, the date you run out and when to ask for a refill.
Arithmetic only, not medical advice. Always follow the directions from your prescriber or pharmacist.
How days supply is calculated
Days supply = quantity ÷ amount used per day. Thirty tablets at one a day last 30 days; 60 tablets at two a day also last 30 days; 90 tablets at one and a half a day last 60 days. The calculator also gives the last day fully covered, the day you run out, and the date to ask for a refill.
Examples
- Twice daily: 60 capsules ÷ 2 per day = 30 days.
- Three times daily, two tablets each: 180 ÷ 6 per day = 30 days.
- Weekly: 4 tablets taken once a week = 28 days (4 weeks).
- Half tablets: enter 0.5 under Taken each time; 30 tablets at half a tablet a day last 60 days.
Refills and planning
- Many insurers and pharmacies allow a refill when about 75 to 80% of the supply has been used, which is around a week early for a 30-day fill. Check your own plan's rule.
- Set the reminder a week or more before you run out, longer around holidays or travel.
- The calendar file works with Apple Calendar, Google Calendar and Outlook and contains only the reminder title and date.
- Liquids, inhalers, insulin and as-needed medicines are calculated differently; ask your pharmacist for those.
Questions
How do I calculate days supply for a prescription?
Divide the quantity dispensed by the number of units taken per day. For example, 90 tablets taken three a day is a 30-day supply.
When will my pills run out?
Enter the quantity, dose, frequency and first dose date. The calculator shows the last day covered and the date you will run out.
When can I refill a 30-day prescription?
Many plans allow it after about 75 to 80% of the supply has been used, roughly 23 to 25 days. Rules differ, so check with your pharmacy or insurer.
Is my medication information stored?
No. The calculation runs in your browser; nothing is saved or sent.
Is this medical advice?
No. It is a simple date calculator. Follow the instructions from your doctor or pharmacist.
From the same developer
- Daily Pills | Reminder: dose reminders and pill supply tracking.
- Track Your Pills: medication tracking and adherence.