Days Supply Calculator
Pharmacy days-supply for tablets, liquids, inhalers and insulin.
Enter your values
Tablets, mL, or units.
Enter the amount per dose you are working with.
Enter the doses per day you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Days supply
- 30 days
- Amount used per day
- 2
- Quantity for 30 days
- 60
- Quantity for 90 days
- 180
Working
- 1Per-day use = 1 × 2 = 2
- 2Days supply = 60 ÷ 2 = 30
Quick answer
Days supply = total quantity dispensed ÷ total amount used per day. For a 30-tablet bottle taken twice daily, days supply = 30 ÷ 2 = 15 days.
Days supply = quantity dispensed ÷ (dose × doses per day)
At a glance
| What it does | Pharmacy days-supply for tablets, liquids, inhalers and insulin. |
|---|---|
| Category | Health |
| Inputs needed | Quantity dispensed, Amount per dose, Doses per day |
| Main output | Days supply |
| Formula | Days supply = quantity dispensed ÷ (dose × doses per day) |
| Cost | Free — no sign-up, no download |
How to use the Days Supply Calculator
- 1Enter the quantity dispensed.
- 2Enter the dose size and how many times a day it is taken.
- 3Read the days supply and the 30/90-day quantities.
Inputs explained
- Quantity dispensed
- Tablets, mL, or units.
- Amount per dose
- Enter the amount per dose you are working with.
- Doses per day
- Enter the doses per day you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Quantity dispensed60
- Amount per dose1
- Doses per day2
Results
- Days supply30 days
- Amount used per day2
- Quantity for 30 days60
- Quantity for 90 days180
- Per-day use = 1 × 2 = 2
- Days supply = 60 ÷ 2 = 30
Frequently asked questions
How do you calculate days supply for insulin?
Add up the total units used per day across all injections, then divide the total units dispensed (for example 1000 units in a box of five 3 mL pens at 100 units/mL) by that daily total.
Do you round days supply up or down?
Insurers almost always require rounding down to whole days, so a 15.6-day calculation is billed as 15 days.
What do I need to enter into the Days Supply Calculator?
Just 3 values: quantity dispensed, amount per dose, doses per day. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Days Supply Calculator work out the answer?
Days supply = total quantity dispensed ÷ total amount used per day. For a 30-tablet bottle taken twice daily, days supply = 30 ÷ 2 = 15 days. It applies the formula Days supply = quantity dispensed ÷ (dose × doses per day) and shows the working so you can check each step by hand.
Is the Days Supply Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.