How to Build a Leitner Box: A Paper Computer for Your Flashcards
A Leitner box is a paper computer program. That sounds ridiculous, but it’s the most accurate description I’ve found—eight dividers inside a card box, running a sorting algorithm that tells you exactly which flashcards to study and when. No battery, no subscription, no notifications. Just cardboard doing the work that apps like Anki do digitally. And there’s a bonus to the analog approach: writing, drawing, and physically handling cards forces you to engage with each word more actively than tapping a screen—which may be why many learners find paper cards stick better.
The idea is simple: cards you know well get reviewed less often, and cards you struggle with keep coming back until they stick. It’s a gauntlet—every card starts at Level 1 and has to fight its way through seven levels before it earns a place in your long-term memory. Fail at any point, and the card drops all the way back to the beginning.
If you’ve read my post on how to make effective flashcards, you already know how to build cards that actually work. This post is the other half: the system that makes sure you review them at the right time.
In this guide: Build a simple spaced-repetition system with just a box and index cards—no app required. Takes about 10 minutes to build, lifetime of effective study.
Table of Contents
- What You’ll Need
- Setting Up the Leitner Box
- How to Play
- The Review Schedule
- Making It Stick
- Try It This Week
What You’ll Need
- A large index card file box. The kind that holds hundreds of cards. Bigger is better—you’ll fill it faster than you think.
- Index cards. A lot of them. Start with a few hundred; you’ll eventually need a couple thousand.
- Eight dividers. These separate your levels. You can buy tab dividers or cut them from cardboard.
- Pens or pencils.
- A calendar you can write on—paper or digital, whatever you’ll actually check every morning.
Everything here is available at a ¥100 shop or stationery store in Fujieda—or anywhere in Japan. The whole setup costs a few hundred yen.
Setting Up the Leitner Box
Sebastian Leitner’s original 1972 system used five compartments. This guide uses a popular seven-level adaptation from Gabriel Wyner’s Fluent Forever that extends the review intervals to 64 days.
Label your eight dividers: New, then Level 1 through Level 7. Place them in the box in order, with “New” at the front.
The “New” section holds cards you’ve just made but haven’t studied yet. When you’re ready to start learning them, move a batch into Level 1. That’s where the game begins.
How to Play
Every card follows the same rules, no exceptions.
Starting out: Each day, move 15–30 new cards from the “New” section into Level 1. Don’t overload yourself—consistency matters more than volume, and this is a habit you want to keep for months, not a sprint you abandon after two weeks.
The test: Pick up a card and ask yourself: “Do I remember what’s on the back?” This means everything—the meaning, the pronunciation, the spelling. If you’re testing a word, you need to recall the full picture, not just a vague sense of familiarity. This is the difference between reviewing and actually recalling, and it’s why most people forget vocabulary even when they study regularly.
If you get it right: The card advances one level. Level 1 to Level 2. Level 4 to Level 5. It moves forward because your memory is getting stronger.
If you get it wrong: The card goes back to Level 1. Not back one level—all the way to the beginning. This sounds harsh, but it’s the point. A card at Level 5 that you can’t remember doesn’t belong at Level 5. The box is honest about what you actually know, not what you think you know.
Retirement: When a card passes Level 7, it’s done. That word has survived seven rounds of increasingly spaced review, and research suggests it’s now in your long-term memory. You can retire the card—or keep it in a “retired” section if you want to revisit once or twice a year.
The Review Schedule
This is where the Leitner box earns the “computer program” comparison. Each level has its own review frequency—a technique called spaced repetition. The pattern roughly doubles each time, but you don’t need to memorize it.
Here’s what you do:
Download and print the 64-day Game Schedule from Fluent Forever. Tape it to the inside of your box lid. Each morning, look at what day you’re on (Day 1, Day 2, Day 3…) and the schedule tells you exactly which levels to review.
That’s it. The schedule does the thinking for you.
If you’re curious about the pattern:
| Level | Rough Frequency |
|---|---|
| Level 1 | Every day |
| Level 2 | Every 2 days |
| Level 3 | Every 4 days |
| Level 4 | Every 8 days |
| Level 5 | Every 16 days |
| Level 6 | Every 32 days |
| Level 7 | Every 64 days |
The actual schedule distributes reviews across a 64-day cycle to keep your daily workload manageable. Just follow the printed schedule—don’t try to calculate it yourself.
Making It Stick
The box only works if you use it consistently. Two things help.
Anchor it to a habit. Review your cards at the same time every day, attached to something you already do—right after your morning coffee, during your commute, before bed. The system does the thinking for you, but you still need to show up. If making this a consistent daily habit feels hard, my guide to using Tiny Habits shows how to anchor new study routines so they become automatic.
Draw on your cards. Paper cards can’t play audio, which means you need another way to anchor pronunciation and meaning. Draw simple pictures—they don’t need to be good. Stick figures work fine. The act of drawing creates a visual memory that helps you recall the word later, and it works especially well for concrete nouns and action verbs.
Try It This Week
You don’t need to build the perfect box before you start. Grab any box, make eight dividers, and move your first 15 cards into Level 1 tomorrow morning. The system will teach you the rest as you go.