Spaced Repetition Schedule Calculator
The review schedule spaced repetition gives a newly learned item — each interval a multiple of the last — with the review dates, how many reviews it takes to reach a long interval, and the daily review load a deck of new cards builds up to.
Memory fades, and a review just before it fades resets the clock for longer.
How the spaced repetition schedule calculator works
Memory fades, and a review just before it fades resets the clock for longer. Spaced repetition schedules reviews at growing intervals — a day, then two or three, then a week, then weeks — each the previous times an ease factor near 2.5. Ten reviews take an item past a year. The catch is load: every card you add today comes back tomorrow, and the deck's daily reviews grow with new cards times the reviews each needs in the period.
Formula: interval₁ = first interval; intervalₙ = intervalₙ₋₁ × ease; reviews to reach T = ⌈log(T / first) / log(ease)⌉ + 1
Worked examples
| Inputs | Reviews to reach the target interval | Note |
|---|---|---|
| The classic 1, 2.5, 6, 16 … schedule | 8 | ten reviews to a year |
| A gentler ease | 10 | more reviews, denser schedule |
| A heavy deck | 8 | hundreds of reviews a day |
FAQFrequently asked questions
What is spaced repetition?
Reviewing something just before you would forget it, at intervals that grow each time you remember. It is the most reliably effective study technique there is, and every flashcard app implements some version.
Where does 2.5 come from?
The default ease factor of the SuperMemo-2 algorithm that Anki and others use. Apps adjust it per card: harder cards get a lower ease and shorter intervals.
Why does the daily load matter?
Because it is what makes people quit. Twenty new cards a day is 100 to 150 reviews a day within a few months; the new-card rate, not the deck size, sets the workload.
What is a lapse?
A failed review — the card goes back to a short interval. A 10% lapse rate is typical; much more means the cards are too hard or too similar.
When is a card learned?
Convention says when its interval passes a few months to a year. This page uses the target interval you set.
Where these figures come from
- Brysbaert (2019), Journal of Memory and Language — How many words do we read per minute? — the 238 wpm silent reading rate, from 190 studies
- US Department of Education — the federal education department
Last checked: September 2026. Reading and writing rates are from published meta-analyses, cited on the page.