The Leitner system for vocabularyFive boxes.
One simple rule.

The Leitner system is a way to review flashcards so that easy words come back rarely and hard words come back often. Cards live in numbered boxes; a right answer moves a card up a box and a wrong answer sends it back to the first. Each box waits longer before its cards return.

Try it in LexpadAll guides

Checked against the app on 3 October 2026.

Boxes
Five
Waits
Today, 1, 3, 7, 21 days
Wrong answer
Back to box 1
Mastered
Box 5, still reviewed

The rule

Sebastian Leitner described the method in the 1970s with paper cards and a box with several compartments. The idea is spaced repetition: you see a word again just before you would forget it, and the gaps grow as you learn it. You spend your time on the words you do not know yet.

  1. Box 1Today
  2. Box 21 day
  3. Box 33 days
  4. Box 47 days
  5. Box 5 · mastered21 days

The intervals Lexpad uses

  • A new word starts in box 1 and is asked today.
  • Answer it right and it moves up one box: box 2 waits 1 day, box 3 3 days, box 4 7 days, box 5 21 days.
  • Get it wrong and it goes back to box 1, to be asked again today.
  • Box 5 counts as mastered, and still returns every 21 days so it stays fresh.
  • Days follow your own time zone.

So a word you know every time is seen today, then after 1, 3 and 7 more days, and reaches box 5 in under two weeks.

Lexpad Progress screen: learning stages from box 1 to box 5 with word counts, 33 mastered and a 24-day streak
Learning stages in Lexpad

Paper box or app

A paper box works, and some people love it. What an app adds is the bookkeeping: it knows which box each word is in and which are due today, it never loses a card, and it can vary the question so a word is not always shown the same way.

In Lexpad, new words start with recognition cards (see the word, recall its meaning); typed recall and spelling unlock once a word reaches box 2. Words you keep mixing up come back together in the Confusables deck.

Making it work

  • Keep sessions short and daily. A few minutes a day beats an hour once a week.
  • Add words you actually met, with the sentence you met them in. Your own words are easier to remember than a list.
  • Be honest when you answer. Moving a word up when you were not sure only brings it back later, when it is harder.
  • Do not worry about missed days. Nothing is lost; due words simply wait for you.

Good to know

Questions

How many boxes should a Leitner system have?

Five is the most common choice, and the one Lexpad uses.

What happens to a word in box 5?

In Lexpad it counts as mastered and comes back every 21 days, so it is not forgotten.

Is the Leitner system the same as spaced repetition?

It is one of the simplest kinds. Other apps calculate a different interval for each card; the Leitner system uses fixed boxes, which makes it easy to understand and trust.

Lexpad

Your next word is worth keeping.

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