Fibonacci vs SM-2 vs Leitner: Which Schedule?

Fibonacci: 1, 1, 2, 3, 5, 8, 13, 21 days

In the Fibonacci sequence each number is the sum of the previous two, so the gaps grow at a moderate pace: review after 1 day, 1 day, 2, 3, 5, 8, 13, 21 days, and so on.

Its strengths are that it is easy to remember and easy to predict. To be straight with you, though, there is no specific evidence that Fibonacci beats other schedules. It is simply a reasonable, simple way to widen the gaps.

Leitner: 1, 3, 7, 14, 30, 60 days

Leitner started as a box system: answer correctly and the card moves to a box with a longer gap. In Fibonacci Review, the Leitner schedule is the sequence 1, 3, 7, 14, 30 and 60 days.

Compared with Fibonacci, Leitner takes bigger jumps, which suits you if you want fewer reviews over the same period.

SM-2: a schedule for each card

SM-2 does not use one fixed sequence. After you answer and flip the card, you rate it Again, Hard, Good or Easy, and the algorithm works out the next date for that card alone. With Good, for example: 1 day the first time, 6 days the second, then multiplied by an ease factor.

Hard cards and easy cards therefore move at different speeds. The trade-off is that you need to rate honestly for the schedule to make sense.

How it works in Fibonacci Review

Flashcards use SM-2. Tasks (study items) let you pick the repeat schedule:

• Fibonacci (the default).
• SM-2 or Leitner.
• Fixed: every 3 days, 1 week, 2 weeks or 1 month.
• Custom, or no repeat at all.

A quick way to choose

For question-and-answer material such as vocabulary or formulas, use flashcards and let SM-2 work card by card. For things you redo, like revising a chapter or practising a question type, you can start with the default Fibonacci and switch to Leitner if the reviews feel too frequent. There is no single right answer, so try one for a few weeks and adjust to how it feels.