Most spaced-repetition apps ask you to trust a black box. This post opens Cotobara's: the exact stages, the exact intervals, and the exact rules for promotion and demotion.
If you want the general theory first, read spaced repetition for Japanese. This is the specific implementation.
The stage ladder
Every word you learn climbs a ladder of nine stages. The interval is how long the word waits after arriving at that stage before it comes back:
| Stage | Next review after |
|---|---|
| New 1 | 4 hours |
| New 2 | 8 hours |
| New 3 | 23 hours |
| New 4 | 47 hours |
| Learning 1 | 7 days |
| Learning 2 | 14 days |
| Familiar | 30 days |
| Known | 120 days |
| Mastered | never again |
A word learned this morning is back in your queue by lunchtime, again this evening, tomorrow, and the day after — the tight early spacing is what stops a brand-new word from evaporating. From there the gaps stretch out fast, and a word you keep getting right costs you a handful of seconds spread over the better part of a year.
Two deliberate details:
- 23 and 47 hours, not 24 and 48. If a word came back exactly a day later it would drift an hour later every cycle, and studying at 9am on Monday would mean studying at midnight by the weekend. Slightly-under-a-day keeps reviews landing at the time you actually study.
- Mastered is final. A Mastered word leaves your queue permanently. There is no resurrection and no burn-undo — when you've earned it, it stops costing you time.
Two cards per word
Here is where Cotobara differs from most SRS setups. Every due word produces two cards:
- Recognition — the Japanese word is shown; you type the English meaning.
- Production — the English meaning is shown; you type the Japanese reading in kana.
The two are deliberately separated in the queue by a few other cards, so answering one doesn't hand you the other.
And here is the rule that matters: a word is graded once, on both cards combined. Get both sides right on the first try and the word promotes. Miss either side, even once, and the word demotes — no partial credit. Recognizing a word without being able to produce it is exactly the gap that shows up in an exam or a conversation, so Cotobara refuses to score it as a win.
What happens when you get one wrong
Missing a word costs you more the higher it had climbed:
- In the New stages (1–4), a miss drops you one stage.
- From Learning 1 upward, a miss drops you two stages.
Forgetting a word you first saw yesterday is normal — that's what the New stages are for. Forgetting a word you supposedly knew for a month means the memory was thinner than the schedule assumed, so the schedule corrects harder.
Within the session itself, a missed card doesn't go to the very back of the queue and it doesn't vanish. It comes back a few cards later — long enough that you're recalling rather than reading off your screen, soon enough that you get a second honest attempt in the same sitting.
Grading is strict about the answer, forgiving about the typing
Cotobara accepts every legitimate meaning a word has — its primary gloss, its alternate meanings, and any custom answers you've added yourself. It also forgives small spelling slips on longer answers, so a stray letter in "convenience" doesn't cost you a word you clearly knew.
What it does not do is quietly pass a wrong answer. And a few checks stop you from scoring yourself unfairly:
- Type a reading into a meaning card and the field shakes instead of grading — you knew the word, you just answered the wrong question.
- Leave stray romaji in a reading answer and it shakes rather than marking you wrong.
On reading cards you type romaji and it converts to kana as you go, so no Japanese IME is required — including on a phone. Hiragana and katakana forms are treated as equivalent, so you're never marked wrong for the script you chose.
Reviews are unlimited, on every plan
Cotobara caps how many new words you take on per day, never how many reviews you clear. The free plan is 3 new words a day; Premium goes up to 100. Your review queue is always fully available, because a review you can't do today is a word you're about to forget.
That cap is the throttle that keeps the system honest: every new word you learn today becomes roughly a dozen reviews spread over the next year. Picking a sustainable daily number is the single highest-leverage setting in the app.
Practising mistakes without touching your schedule
Sometimes you just want to drill the words that keep beating you. Cotobara's recent-mistakes practice is a quick flip-card loop over your latest misses that is completely ungraded — it never submits, never promotes, never demotes. It's a warm-up, not a review, and it's deliberately walled off from your SRS so a practice round can't distort the schedule that's doing the real work.
Why this shape
The intervals aren't arbitrary. Each one sits near the point where you're about to forget — the moment when a successful recall does the most to strengthen the memory. Reviewing sooner is wasted effort; reviewing later means relearning from scratch. Nine stages is enough to cover four hours to four months without any gap so large that words fall through it.
The rest is just showing up. The schedule handles what to study and when; you only have to answer honestly.
Start for free and learn your first five words — the first review lands four hours later.