Spaced Repetition Interval Calculator
Choose how each review of a flashcard goes, and see the gap to the next review and the date it falls on. It works instantly and needs no account. The numbers come from the scheduler inside Fulin Flashcard, an SM-2-style rule where each card carries its own ease and the interval multiplies by it.
Your card's schedule
| Review | Grade | Reviewed on | Gap until next | Next review | Ease |
|---|---|---|---|---|---|
| 1 | Good | Day 0 | 1 day | Day 1 | 2.5 |
| 2 | Good | Day 1 | 2.5 days | Day 3.5 | 2.5 |
| 3 | Good | Day 3.5 | 6.25 days | Day 9.8 | 2.5 |
| 4 | Good | Day 9.8 | 15.63 days | Day 25.4 | 2.5 |
| 5 | Good | Day 25.4 | 39.08 days | Day 64.5 | 2.5 |
| 6 | Good | Day 64.5 | 97.7 days | Day 162.2 | 2.5 |
Assumes you review each time the card is due. Gaps under a day are shown in hours in the gap column and rounded to the same calendar day in the date columns.
Want a deck that schedules cards this way for you?
Try Fulin Flashcard freeThe model and its assumptions
- A new card starts at an ease of 2.5. Ease moves between 1.3 and 2.5.
- New card: Again returns in 4 hours, Hard in 12 hours, Good in 1 day, Easy in 30 days and the card is retired from review.
- Graduated card: Good multiplies the interval by ease. Hard multiplies it by 1.2 and lowers ease by 0.15. Easy multiplies it by ease and 1.3, raises ease by 0.15 and retires the card. Again returns in 4 hours and lowers ease by 0.2.
- Intervals are capped at 730 days and each review happens exactly when due.
- Dates are UTC calendar days. This is one card in isolation: it does not estimate how many cards you will see per day.
Frequently asked questions
- How is the next review date calculated?
- The calculator runs one card through the same scheduling function Fulin Flashcard uses. A new card starts at an ease of 2.5. Good on a new card schedules the first review 1 day out. After that, each Good multiplies the current interval by the card's ease, so with the default ease the gaps are 1, 2.5, 6.25, 15.63 days and so on.
- What happens when I press Again?
- The card comes back after 4 hours and its interval resets to zero. If the card had already graduated from the learning step, its ease also drops by 0.2, down to a floor of 1.3, so a word you keep forgetting returns more often from then on.
- What do Hard and Easy do?
- On a card still in learning, Hard brings it back in 12 hours and Easy sends it 30 days out and retires it from review. On a graduated card, Hard multiplies the interval by 1.2 (at least 1 day) and lowers ease by 0.15. Easy multiplies the interval by the ease and by 1.3, raises ease by 0.15 (capped at 2.5) and retires the card, which is why the table stops there.
- Is this the same as the Anki scheduler?
- No. It is an SM-2-style scheduler, the same family as Anki's classic one, but Anki has its own learning steps, interval modifiers and fuzz, and its newer FSRS option uses a different memory model. Use this page to understand how a multiplying-interval schedule behaves, not to predict an Anki deck to the day.
- Does it handle late reviews or a maximum interval?
- It assumes every review happens exactly on the due date, so late reviews are not modelled. Intervals are capped at 730 days, the cap the app uses.
- Is this a forgetting-curve prediction?
- No. The calculator does not estimate how much you will remember. It only applies a scheduling rule to the grades you choose, so it shows when a card would be due, not the chance you recall it.