Days Supply Calculator
Free days supply and prescription refill calculator for pharmacy technicians. Enter the quantity dispensed and the sig to get the day supply for tablets, liquids, inhalers, insulin, eye drops, and topicals, with the math shown step by step.
The formula
Days supply = total quantity dispensed divided by the amount used per day. The only part that changes by dosage form is how you measure the daily amount: tablets per day, mL per day, units per day, drops per day, puffs per day, or grams per day.
Choose your medication type
Pick the dosage form you are filling. The calculator jumps to the matching tab and the worked medication guides appear below.
Interactive calculator
Select a medication type or pick a quick example below
Alabama Days Supply Cheat Sheet
One printable page with the days supply math Alabama pharmacies check at the bench and on every insurance claim.
- Tablets, capsules, and tapers using the whole number rounding Alabama pharmacies expect
- Insulin vials and pens, with units per package worked out for you
- Inhalers, puffs, eye drops, and mL to drops conversions
- The same math taught in the ALBOP approved technician training program from Dalton Pharmacy
The days supply calculator stays free. Built by Tyler Dalton, PharmD.
Every free calculator in one place
Need a faster answer for one dosage form or a refill date? These calculators run the same math with the package sizes and billing rules already built in.
- Free ToolsCalculators and quick-reference guides for pharmacy technicians
- Refill CalculatorNext refill date, run out date, and the earliest date insurance will pay
- Insulin Day Supply CalculatorVials and pens converted to units, divided by total daily units
- Eye Drop Day Supply CalculatormL to drops, one eye or both, with bottle size quick reference
- Tablet Day Supply CalculatorPills and capsules, including every other day and weekly sigs
- mg to mL Dose CalculatorConvert a milligram dose to millilitres and get the liquid days supply
- Cream Day Supply CalculatorGrams per day with a fingertip unit chart by body area
- Inhaler Day Supply CalculatorActuations divided by puffs per day for albuterol and maintenance inhalers
Meet your Alabama training requirement
Days supply is the math you will use at the bench. Alabama Pharm Tech is ALBOP-approved training that walks you through this math step by step, plus everything else you need to finish on time.
- ALBOP-approved training program
- Start today, finish on your schedule
- Pharmacy math practice with worked solutions
- One payment of $199, everything included
Top drug day supply guides
Worked examples for insulin, GLP-1s, inhalers, and the most searched medications.
Looking for a medication that is not listed? Browse all medication day supply guides.
How do you calculate days supply for tablets?
Divide the quantity dispensed by the number of tablets taken per day. Daily tablets = tablets per dose × doses per day. For example, 90 tablets at 1 tablet twice daily (BID) = 90 ÷ 2 = 45 days supply.
How do you calculate days supply for insulin?
A standard insulin vial is 10 mL at 100 units/mL = 1,000 total units. An insulin pen cartridge is 3 mL = 300 units. Multiply packages × units per package, then divide by total daily units. Example: 1 vial, 40 units/day = 1,000 ÷ 40 = 25 days.
How do you calculate days supply for eye drops?
Convert mL to drops using the standard rate of 20 drops/mL, then divide by drops used per day (drops per dose × doses per day × number of eyes). For Latanoprost 2.5 mL, 1 drop at bedtime in one eye: 50 total drops ÷ 1 = 50 days supply.
How do you calculate days supply for inhalers?
Total puffs = puffs per inhaler × number of inhalers. Daily puffs = puffs per dose × doses per day. Days supply = total puffs ÷ daily puffs. Albuterol 200 puffs, 2 puffs 4 times daily = 200 ÷ 8 = 25 days supply.
Frequently Asked Questions
Why does days supply matter for insurance billing?
Insurance plans set limits on how early a refill can be processed (usually when 75–80% of days supply is used). An incorrect days supply can cause claim rejections or allow early refills that are flagged as dispensing errors.
What is the days supply formula for creams and ointments?
Days supply = quantity dispensed (grams) ÷ (grams per application × applications per day). A 30 g tube used 1 g twice daily = 30 ÷ 2 = 15 days.
How do patches work for days supply?
Days supply = patches dispensed ÷ patches used per day. A patch worn every 3 days = 0.33 patches/day. 30 patches ÷ 0.33 = 90 days supply.
Is this calculator approved for use in Alabama pharmacies?
This tool is for educational and reference purposes only. Always confirm days supply calculations in your pharmacy dispensing system and consult the pharmacist for complex or ambiguous prescriptions.