Days Supply for Liquid Medication
Days Supply = Bottle Volume (mL) ÷ (Dose in mL × Doses per Day)
| Bottle | Dose | How often | mL per day | Days supply |
|---|---|---|---|---|
| 150 mL | 5 mL | Twice daily | 10 | 15 days |
| 100 mL | 7.5 mL | Twice daily | 15 | 6 days (6.7) |
| 200 mL | 10 mL | Three times daily | 30 | 6 days (6.7) |
| 473 mL (16 oz) | 15 mL | Once daily | 15 | 31 days |
As with tablets, round down: a partial day doesn't cover all of that day's doses.
Teaspoons, Tablespoons and mL
US pharmacies label most liquid doses in milliliters. If your directions use spoons, these are the standard medical measures:
- 1 teaspoon (tsp) = 5 mL
- ½ teaspoon = 2.5 mL
- 1 tablespoon (tbsp) = 15 mL
Kitchen spoons aren't reliable; real teaspoons range widely in size. Always measure with the oral syringe, dropper or dosing cup that came with the medicine, or ask the pharmacy for one.
Why Bottles Run Out Early
It's normal for a liquid to run out a little before the math says. Small amounts get left in the syringe or cup, coat the inside of the bottle, or spill. Thick suspensions lose more than thin solutions. Choosing a 5% loss allowance gives a more realistic date; use 10% for very thick liquids or if doses are often spilled.
If you're running short well before the refill date, call the pharmacy. They can check whether the dose is being measured correctly and contact the prescriber if needed.
Discard Dates on Mixed Suspensions
Some liquids, especially antibiotic suspensions mixed with water at the pharmacy, only stay good for a limited time, often 10 to 14 days and sometimes only if refrigerated. The label gives the "discard after" date.
Enter that number of days and the calculator compares it with the run-out date. If the discard date comes first, you'll see roughly how much will be left so you know to throw it away then, not save it for later. Leftover antibiotic shouldn't be kept for a future illness.
For Children's Medicine
This calculator works out how long a bottle lasts. It does not calculate doses. Children's doses depend on weight and age and must come from the label, the prescriber or a pharmacist. If you're unsure how much to give, call the pharmacy before giving it.
For tablets and capsules, use the days supply calculator or the pill refill date calculator.