The Leitner system, explained

By Ahmed Eltigani · Updated 19 October 2026

What is the Leitner system?

The Leitner system is a way of studying flashcards with a few boxes. Every card starts in box 1. When you remember a card, it moves up one box and comes back less often. When you forget it, it goes back to box 1. Hard cards keep coming back; easy ones fade into the background.

That's the whole method. You don't need an algorithm, a spreadsheet or a scoring system. You need cards, boxes, and the honesty to say "I didn't know that one."

Where does the Leitner system come from?

It was popularised by Sebastian Leitner (1919–1989), a German science journalist and commentator. He described it in his 1972 book So lernt man lernen. Der Weg zum Erfolg ("How to learn to learn: the way to success"), published by Verlag Herder in Freiburg (Wikipedia: Sebastian Leitner, checked 19 October 2026). Herder published an 18th edition in 2011.

His original box didn't run on a calendar. According to Wikipedia's article on the Leitner system (checked 19 October 2026), the card box had five partitions of growing size, 1, 2, 5, 8 and 14 cm deep, and you reviewed a partition when it filled up. Bigger partitions took longer to fill, so cards further back came round less often.

Most apps, Lietner included, swap the partition sizes for fixed day intervals. The idea is the same: the further a card has climbed, the longer it waits.

How does the 5-box Leitner system work?

Lietner uses five boxes with intervals that double each time:

The rules are short:

• New cards start in box 1 and are due straight away.
• You grade yourself. Knew it moves the card up one box. Missed sends it back to box 1, due tomorrow.
• Knowing a card in box 5 masters it, and it leaves the rotation.
• Each session reviews every card that's due today.

Here is one card's path if you never miss it. You learn it on day 0 and it moves to box 2. You see it again on day 2 (box 3), day 6 (box 4), day 14 (box 5) and day 30, when it's mastered. That's five reviews in a month. Miss it on day 14 and it's back in box 1, due on day 15.

Why does the Leitner system work?

It combines two of the best-supported findings in learning research.

Spacing. Reviews spread out over time beat the same amount of cramming. A 2006 meta-analysis by Cepeda and colleagues pulled together 839 assessments of spaced practice from 317 experiments, and found that the best gap between study sessions grows with how long you need to remember the material (Psychological Bulletin, PubMed 16719566, checked 19 October 2026). Leitner's growing intervals build that in.

Testing yourself. Trying to recall an answer strengthens memory more than rereading it. In Roediger and Karpicke's 2006 experiments, students who restudied a text did better on a test five minutes later, but students who had tested themselves remembered much more two days and a week later. The restudiers felt more confident all the same (Psychological Science, PubMed 16507066, checked 19 October 2026).

A 2013 review of ten common study techniques by Dunlosky and colleagues rated only two as "high utility": practice testing and distributed practice. Rereading and highlighting were rated low (Psychological Science in the Public Interest, PubMed 26173288, checked 19 October 2026). Every flashcard is a small practice test, and the boxes do the distributing.

Should I use a paper Leitner box or an app?

Both work. Pick the one you'll actually use.

Writing cards by hand is slow, and that slowness can be useful. An app wins when you have hundreds of cards, study in short gaps during the day, or keep losing track of which partition is due.

How is the Leitner system different from Anki's algorithm?

Anki and SuperMemo use algorithms that set a separate interval for every card. SM-2, released with SuperMemo in 1987, adjusts each card's "ease" based on a 0–5 grade (Wikipedia: SuperMemo, checked 19 October 2026). FSRS, the Free Spaced Repetition Scheduler, goes further and uses machine learning to fit your own memory patterns (open-spaced-repetition/fsrs4anki, checked 19 October 2026). Anki 23.10 and later support FSRS as an option you turn on in deck options (Anki manual: Deck Options, checked 19 October 2026).

An adaptive algorithm can schedule each card more precisely, which matters most when you're keeping thousands of cards for years, as many medical students do. The Leitner system trades some of that precision for something you can understand at a glance. For a term's worth of vocabulary or an exam next month, that trade is usually fine.

How do I start using the Leitner system?

You can build a paper box this afternoon, or open Lietner and use five boxes on a 3D desk instead. Lietner is free, works offline, and needs no account. To get your first cards in:

• type them in the deck editor;
• ask your own AI to write them from your notes;
• or import an Anki deck or a CSV file.

Then review whatever is due each day. The boxes do the rest.

Where do these facts come from?

All links were checked on 19 October 2026.

• Sebastian Leitner and Leitner system, Wikipedia.
• Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354–380. PubMed.
• Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science. PubMed.
• Dunlosky, J., et al. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest. PubMed.
• SuperMemo, Wikipedia; fsrs4anki, GitHub; Deck Options, Anki manual.