# When is my next refill?

Finds the earliest date a pharmacy can refill a prescription, once 75% (or another share) of the days’ supply has passed, and the day the supply runs out.

- Page: https://www.acalculator.org/days/prescription-refill-calculator
- JSON spec: https://www.acalculator.org/days/prescription-refill-calculator.json
- Version: b5ae25bc580a

## Default answer

Example with the default inputs (Date last filled September 12, 2026, Supply given as Days’ supply, Days’ supply 30, Share of the supply to use first 75%, Count from October 2, 2026) on the example date Friday, October 2, 2026: Filled on September 12, 2026 with 30 days’ supply, the earliest refill is Monday, October 5, 2026; the supply runs out on Monday, October 12, 2026.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| fill | Date last filled | The day the pharmacy last filled the prescription. |
| by | Supply given as | Type the days’ supply on the label, or the number of pills and how many you take a day. |
| ds | Days’ supply | How many days the fill lasts, as on the label: often 30 or 90. |
| qty | Pills (or doses) dispensed | How many pills, tablets or doses the pharmacy gave you. |
| pd | Pills (or doses) per day | How many you take each day. |
| pct | Share of the supply to use first | How much of the days’ supply must pass before a refill, as your plan sets it: often 75%, more for controlled drugs. |
| on | Count from | The date to count the days from. Today, unless you change it. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| earliest | Earliest refill date | The fill date plus the days to wait: the first day a refill is due under the share chosen. |
| status | Refill | Whether a refill is due on the count-from date, or in how many days. |
| wait | Days from fill to refill | The days’ supply × the share, rounded up to a whole day. |
| runOut | Supply runs out | The fill date plus the days’ supply: the first day with no medicine left. |
| daysLeft | Days of supply left | Days from the count-from date to the day the supply runs out; 0 once it has run out. |
| supplyDays | Days’ supply | The days the fill lasts: as typed, or the pills ÷ the pills per day, rounded down. |

## Method

Days to wait = ⌈days’ supply × share ÷ 100⌉; earliest refill = date filled + days to wait; supply runs out = date filled + days’ supply.

## Assumptions

- Plans set the share; Colorado Medicaid, for example, uses 75% of the days’ supply, and 85% for controlled drugs. Check your own plan.
- Days are calendar days; the fill date is day 0.
- From pills and a daily dose, the days’ supply is the whole days the pills last (pills ÷ pills per day, rounded down).
- This is a date guide, not medical or insurance advice; the pharmacy and the plan decide.

## Worked examples

1. fill = 2026-09-01, by = days, ds = 30, pct = 75%, on = 2026-09-10 gives wait = 23, earliest = 2026-09-24, status = Refill due in 14 days, runOut = 2026-10-01, daysLeft = 21, supplyDays = 30. Source: Colorado Department of Health Care Policy and Financing, Pharmacy Billing Manual (refill too soon: 75% of the days’ supply for non-scheduled drugs, 85% for Schedule II to V), https://hcpf.colorado.gov/pharmacy-billing-manual, retrieved 2026-10-02.
2. fill = 2026-01-15, by = days, ds = 90, pct = 85%, on = 2026-04-20 gives wait = 77, earliest = 2026-04-02, status = Refill due now, runOut = 2026-04-15, daysLeft = 0. Source: Colorado Department of Health Care Policy and Financing, Pharmacy Billing Manual (refill too soon: 75% of the days’ supply for non-scheduled drugs, 85% for Schedule II to V), https://hcpf.colorado.gov/pharmacy-billing-manual, retrieved 2026-10-02.
3. fill = 2026-02-20, by = pills, qty = 45, pd = 2, pct = 80%, on = 2026-02-20 gives supplyDays = 22, wait = 18, earliest = 2026-03-10, runOut = 2026-03-14.
4. fill = 2028-02-01, by = days, ds = 30, pct = 100%, on = 2028-02-29 gives earliest = 2028-03-02, status = Refill due in 2 days.

## FAQ

### How early can I refill a prescription?

Plans let a refill go through once a set share of the days’ supply has passed, and the share is higher for controlled drugs. Colorado Medicaid, for example, uses 75% for ordinary drugs and 85% for DEA Schedule II to V drugs. For a 30-day supply at 75%, that is day 23.

### How is the refill date worked out?

Multiply the days’ supply by the share and round up to a whole day, then add that many days to the fill date. 30 × 0.75 = 22.5, which rounds up to 23, so a fill on September 1 can be refilled from September 24.

### When is a 90-day prescription due for a refill?

At 75%, after ⌈90 × 0.75⌉ = 68 days; at 80%, after 72 days; at 85%, after 77 days. Add the days to the fill date.

### What if I only know the number of pills?

Choose Pills and dose, and type the pills dispensed and how many you take a day. 45 pills at 2 a day last 22 whole days, which the calculator uses as the days’ supply.

### What does refill too soon mean?

A pharmacy claim the plan turns down because not enough of the last fill’s days’ supply has passed. A change in dose, a lost supply, or travel may allow an override; ask your pharmacy.

### When does my supply run out?

On the fill date plus the days’ supply. A 30-day fill on September 1 runs out on October 1, the first day with no medicine left if you take it as prescribed.

## Sources

- Colorado Department of Health Care Policy and Financing, Pharmacy Billing Manual, Refill Too Soon Policy (75% of the days’ supply for non-scheduled drugs, 85% for DEA Schedule II to V), retrieved 2026-10-02. https://hcpf.colorado.gov/pharmacy-billing-manual