This works as a prescription quantity calculator too: if a prescription says "30-day supply" without a number, or you want to check that the quantity on your label covers the days you need, enter your directions and the number of days.
The Quantity Formula
Quantity = Amount per Dose × Doses per Day × Number of Days
Then round up to a whole tablet or capsule, since you can't be dispensed part of one.
| Directions | Days | Calculation | Quantity |
|---|---|---|---|
| 1 tablet three times daily | 10 | 1 × 3 × 10 | 30 |
| 2 capsules twice daily | 14 | 2 × 2 × 14 | 56 |
| ½ tablet daily | 25 | 0.5 × 1 × 25 = 12.5 | 13 |
| 1 tablet every other day | 30 | 15 doses × 1 | 15 |
| 1 tablet once a week | 30 | 5 doses (days 1, 8, 15, 22, 29) | 5 |
For weekly and every-other-day schedules, the calculator counts actual doses rather than multiplying an average. Once a week for 30 days is 5 doses, not 4.3, if you take the first dose on day 1.
Planning for Travel
Before a trip, work out how many tablets you need from today until you're home, then compare with what you have:
- Enter your dose and the number of days until you return.
- Add spare days to allow for delays. Many travelers pack two to three days extra.
- Count what you have. If it's short, ask your pharmacist about an early or vacation fill well before you go.
If you track your medications in RefillDay, the trip check in My Medications does this for all of them at once.
Keep medications in their original labeled containers when flying, and carry them in your hand luggage. Rules for traveling abroad with certain medications vary by country, so check before an international trip.
When Your Prescription Quantity Is Different
The quantity your prescriber writes isn't always the exact number your directions need:
- Package sizes. Some medications come in fixed packs such as 28 or 30, and quantities are rounded to match.
- Plan quantity limits. Insurance may pay for no more than a set number of units in a period.
- Days-based prescribing. Prescribers often write "30-day supply" and let the pharmacy calculate the quantity.
- Titration. When a dose is being increased step by step, the quantity covers the whole schedule.
If your quantity seems too small to last until your next refill, mention it to the pharmacist at pickup. That's much easier to fix than a gap later.
Related Calculations
To go the other way (how long a quantity will last) use the days supply calculator. If your dose is in milligrams and you need to know how many tablets that is, start with the tablets and capsules calculator.