DecksAnki ease factor explained: what 250% means and how it changes
Ease is the number Anki multiplies a card's interval by when you press Good, so a card at 250% ease that's due every 10 days comes back in about 25 days. Every card starts at 250%, loses points when you press Again or Hard, gains them when you press Easy, and never drops below 130%.
Ease only exists in Anki's default SM-2 scheduler. If you've turned on FSRS in your deck options, Anki doesn't use ease at all (more on that below).
Where the number comes from
Ease comes from SuperMemo's SM-2 algorithm, where it's called the E-Factor. SM-2 starts every item at 2.5 and never lets it fall below 1.3; Anki kept both numbers and shows them as percentages, so 2.5 is 250% and 1.3 is 130%.
How each rating changes ease
Ease only changes on cards that have finished their learning steps. While a card is new or relearning, its ease stays where it is.
| Rating | Ease change | 250% becomes |
|---|---|---|
| Again | −20 points | 230% |
| Hard | −15 points | 235% |
| Good | no change | 250% |
| Easy | +15 points | 265% |
The floor is 130%. There's no ceiling: a card you keep rating Easy keeps climbing.
How ease sets the next interval
Take a review card that is due every 10 days, with 250% ease, reviewed on its due day, with Anki's default settings:
| Rating | Next interval | Calculation |
|---|---|---|
| Again | 10 minutes, then 1 day | Relearning step, then 10 × New interval (0%), raised to the 1-day minimum |
| Hard | 12 days | 10 × Hard interval (1.2) |
| Good | 25 days | 10 × ease (2.5) |
| Easy | about 33 days | 10 × ease (2.5) × Easy bonus (1.3) |
A few details change the exact number you see on the buttons:
- Anki uses the ease the card had before you answered. The Easy row above multiplies by 2.5, not the new 2.65.
- Late reviews count for something. If you review a card late, Anki adds half the days late before multiplying for Good, and all of them for Easy.
- Minimums. Hard always gives at least one day more than the current interval, Good at least one day more than Hard, and Easy at least one day more than Good.
- Fuzz. Anki nudges intervals by a small random amount so cards you learned together don't all fall due on the same day. Your buttons can differ from the table by a day or two.
Why a few points of ease matter
Ease compounds. Each Good review multiplies the interval by the ease, so after five Good reviews in a row (ignoring rounding and fuzz):
| Ease | Interval multiplied by | A 10-day card ends up at |
|---|---|---|
| 250% | about 98 | about 980 days |
| 200% | 32 | 320 days |
| 160% | about 10.5 | about 105 days |
| 130% | about 3.7 | about 37 days |
So a card stuck at 130% keeps coming back every few weeks for years, where a card at 250% would be out of the way. That's why low-ease cards come to dominate your reviews, and why Anki users talk about ease hell.
Where to see and change it
- A card's ease: open the Browse window and add the Ease column, or open Card Info during review.
- Starting ease: Deck Options, Advanced section, default 2.50. Changing it only affects cards when they next graduate from learning; cards already in review keep their own ease.
- Related settings: Easy bonus (default 1.30), Hard interval (1.20) and Interval modifier (1.00) are in the same section; New interval (0.00), the share of the old interval a card keeps after Again, is also under Advanced. Interval modifier scales every review interval; leave it at 1.00 unless you've measured your retention and want to trade more reviews for fewer lapses or the other way round.
Rating habits that keep ease healthy
- Press Again when you got it wrong. Rounding a miss up to Hard keeps the ease a bit higher but schedules the card too far out, so you miss it again.
- Don't use Hard for "correct but slow". It costs 15 points every time. If you got it, press Good. What each rating does goes through this in detail.
- Press Easy when a card is genuinely easy. It's the only way ease goes back up.
- Rewrite cards you keep failing. Repeated lapses mean −20 each time. A card that's failed many times usually has too much on it; see how to write good flashcards.
What happens with FSRS
FSRS replaces ease with its own per-card estimates, including a difficulty value, and schedules each review for the day it predicts your recall will fall to your desired retention (90% by default). When you turn FSRS on, Anki hides the SM-2 options such as Starting ease and Easy bonus. FSRS is off by default. The two schedulers are compared in SM-2 vs FSRS.
In Decks
Decks uses SM-2 with the same starting ease (250%), the same changes per rating and the same 130% floor. One difference: Decks applies the new ease straight away, so Easy on the 10-day card above gives 34 days (10 × 2.65 × 1.3) rather than about 33. Decks doesn't offer FSRS, and its ease settings can't be changed.
Published 2026-10-13. Updated 2026-10-22.