Spaced Repetition Schedule Calculator
Enter when you start learning and how many word groups you plan to study. Get a day-by-day review timetable based on the Ebbinghaus forgetting curve — exportable to your calendar.
One group = one day of new material, e.g. 20 words
Why these intervals? The forgetting curve
How the classic 40-day review plan works
The classic plan reviews each new group 1, 2, 4, 7 and 15 days after learning. Study one group a day for 25 days and the final review lands on day 40.
The short early intervals catch the steepest part of forgetting; the later gaps widen as successful recall strengthens the memory.
A fixed table is useful for understanding spaced repetition or studying on paper. An FSRS app instead schedules every card from what you actually remembered, so it can adapt when a review feels easy or hard.
FAQ
What are the best spaced repetition intervals?
A practical schedule reviews each item 20 minutes after learning, then 1 day, 3 days, 1 week, 1 month, and 3 months later. After about six well-timed reviews, material is effectively in long-term memory. The exact optimum varies per person — that is what adaptive algorithms like FSRS solve.
Why review 20 minutes after learning?
The forgetting curve is steepest right after learning: about 42% is forgotten within 20 minutes. One quick review in that window flattens the curve dramatically and makes every later review cheaper.
What is the classic 40-day plan?
The textbook Ebbinghaus plan reviews each group 1, 2, 4, 7 and 15 days after learning it. If you learn 25 groups on 25 consecutive days, the last review lands on day 40 — hence the name.
Do I still need this table if I use an SRS app?
No — that is the point of SRS apps. KaChiKa and Anki schedule each card individually based on your actual recall, which beats any fixed table. This calculator is for paper-based studying or understanding how spaced repetition works.