How WaniKani SRS works (and why 4h, 8h, 23h, 47h)
Spaced Repetition Software is a glorified flashcard timer. You see an item, you answer it, the algorithm decides when to show it to you next. The interesting part is the spacing curve - the gaps between reviews grow as you prove you remember. WaniKani uses a fixed table of intervals rather than a learned curve like Anki, which makes it predictable and beatable but also rigid.
This guide is the full interval table, what each stage means in practice, and the subtle bits about how WaniKani actually decides what counts as a passing review.
The interval table
Each bar shows the wait before the next review at that stage. Bars use a sqrt scale so short waits stay legible.
What each stage means
| Stage | Wait | Means |
|---|---|---|
| Lesson | unlocked | Available to learn for the first time |
| Apprentice I | 4h | Just learned. Reviewed in 4 hours. |
| Apprentice II | 8h | Same day, a second look |
| Apprentice III | 23h | Next-day review (1d colloquially) |
| Apprentice IV | 47h | Two-day wait. Pass = Guru. |
| Guru I | 7d | Counts toward levelling up |
| Guru II | 14d | Two-week wait |
| Master | 30d | Monthly check-in |
| Enlightened | 120d | Four months. Pass = Burn. |
| Burned | done | No more reviews. The item is yours. |
What "passing" actually means
A passing review on WaniKani is not "got it right". Most items have a meaning AND a reading. You have to answer both correctly within a single review session for the item to advance one stage. Get one right and one wrong and the item drops back instead of advancing.
The exact drop is a function of how many times you got it wrong. Each incorrect answer in a session demotes the item by one or two stages depending on its current SRS level. A Master item that you whiffed twice can drop all the way back to Apprentice IV, which means an extra week before it tries again.
The 90% level-up rule
You level up when 90% of your current level's kanji reach Guru I or higher. Radicals do not count toward the 90% rule, but they unlock the kanji you need to study. The vocab in your current level can drag behind and you will still level up; it stays in your queue.
The fastest theoretical path through a level - assuming radicals are already Guru'd when you arrive - is the 82-hour walk from a fresh kanji lesson to Apprentice IV: 4 + 8 + 23 + 47 = 82 hours, or 3 days 10 hours. That is the math floor. In practice radicals stack at least another 3-4 days on top.
Accelerated levels 1-2
Levels 1 and 2 use an accelerated SRS where Apprentice waits are halved: 2h / 4h / 8h / 23h. This is why your first two levels feel unreasonably fast and then everything decelerates. From level 3 onward you are on the standard table above.
Why these specific intervals
The interval gaps roughly double at each transition until Enlightened, which is a classic spaced-repetition pattern. Tofugu has never published a derivation, but the curve is calibrated to keep recall in the 80-90% range across the population. Items you forget at Guru II are common; items you forget at Enlightened are rare but not unheard-of. The system is designed to be reviewed at imperfect accuracy.
The 23h and 47h waits (sold colloquially as "1d" and "2d") are slightly under the round number on purpose: it lets the next review fit into the same hour-of-day slot as the previous one, so a morning learner stays a morning learner instead of drifting later each day.
See your own SRS distribution
The full Wanilog dashboard breaks down how many items you have at each stage, your accuracy trend over time, and the items most likely to drop on the next review. Sign in with your API key to see it. Your key stays in your browser.