Leitner System vs Spaced Repetition: How to Schedule Reviews

The two terms are often used as if they mean the same thing. Both spread reviews over time, and both are more effective than reading a deck once. The difference is in how the schedule is made: the Leitner system moves cards through a small number of fixed boxes, while spaced repetition gives each card its own interval based on how well you recalled it.

Flashcards builds a deck from your notes and supports review with active recall. The comparison below is about the schedule around the cards, not the software. You can run either method with paper index cards if you prefer.

How the Leitner system works

The system is easy to understand and easy to audit: you can see how many cards are in each box and which ones keep returning. It also makes the cost of a wrong answer obvious, because the card drops back to daily review. Some people move a missed card back only one box rather than all the way to the start; both versions are used, so decide which one you are following.

How spaced repetition works

Spaced repetition uses the same underlying finding — that recall is stronger when review is spread out — but it schedules each item separately. A card answered easily gets a longer interval; a card answered with difficulty gets a shorter one. Many apps use an algorithm to adjust the next review date, so a large deck can contain hundreds of different due dates.

Which schedule should you use?

Choose Leitner when the deck is small, the material is fairly uniform, and you want a method you can run without software. It suits definitions, vocabulary, and short facts where a card is either right or wrong. Choose per-card spaced repetition when the deck is large, the items vary in difficulty, or your study days are irregular. The software can absorb the administration that would otherwise take longer than the review.

Both methods depend on the cards. A vague question produces a vague answer and a useless review, whichever schedule you use. Keep one idea per card and make the answer specific enough to check. If a card keeps failing, rewrite it before you blame the interval.

Schedules are an aid, not a guarantee

A review schedule decides when you see a card; it does not decide whether the memory will stay. Understanding the material, connecting it to what you already know, sleeping well, and testing yourself rather than recognising the answer all matter. A card reviewed on the perfect day can still be forgotten next month.

Pasted material is sent to a server to build the deck, while the deck itself stays in your browser. Do not paste personal notes, private student records, or anything you would not put in an email. The page states what is sent. For the card-writing method, read How to Write Good Flashcard Questions. For the broader routine, see How to Make Flashcards That Actually Work.

Start with a small deck in Flashcards, choose a schedule you will actually keep, and review the cards that are due. The method matters less than consistent retrieval with cards that test one clear idea.