The Leitner system is a flashcard method that sorts cards into a series of numbered boxes. Each time you answer a card correctly, it moves to the next box, which you review less often; each time you get it wrong, it goes back to the first box, which you review most often.
How it works
The Leitner system is a simple, physical form of spaced repetition. Cards you know well gradually move into boxes you rarely review, while cards you struggle with stay in box one and come up every session. That means your time goes where it is needed most, and well-learned cards are still reviewed occasionally so they do not fade.
Because every review requires you to answer before turning the card, the system also builds in active recall.
How to use the Leitner system (steps)
- Make cards. Write one question per card with the answer on the back. See flashcards for tips on good cards.
- Set up boxes. Label three to five boxes or envelopes, for example Box 1 to Box 5.
- Assign a schedule. For example: Box 1 every day, Box 2 every two days, Box 3 every four days, Box 4 weekly, Box 5 every two weeks.
- Start everything in Box 1.
- Review due boxes. Answer each card aloud or on paper before flipping. Correct cards move up one box; wrong cards go back to Box 1.
- Retire or keep. Cards that pass Box 5 can be retired or kept in a final box for occasional review before an exam.
Evidence
Sebastian Leitner described the system in 1972 in So lernt man lernen. The method itself has been studied less than the principles it relies on, but those principles are among the most robust in learning science. Ebbinghaus’s 1885 work on the forgetting curve showed that spaced repetitions improve retention, Cepeda and colleagues’ 2006 meta-analysis confirmed the benefit of distributed practice, and Roediger and Karpicke (2006) showed that testing yourself beats restudying. Kornell (2009) found that studying flashcards in one large, spaced stack produced better learning than studying in small, massed stacks, which supports the Leitner approach of revisiting each card after a gap.
Using the Leitner system with Duetoday
Duetoday’s flashcards apply the same idea automatically. Generate a deck from a lecture, PDF or YouTube video with the AI flashcard generator, and built-in spaced repetition decides which cards are due each day, without boxes to manage. Prefer paper? Export your deck to CSV and print it, or export to Anki.
