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Tison Brokenshire

Updated on 2/21/2026

Spaced Repetition Schedule Cheat Sheet: Every System Compared

You study for hours. You highlight, re-read, and take notes. A week later, you sit down for the exam and realize most of it is gone. The material felt familiar yesterday, but now the details blur together. This is not a failure of effort. It is a failure of timing.

Cramming packs information into short-term memory, where it decays within days. Research on the Ebbinghaus forgetting curve shows that people forget roughly 70 percent of new material within 24 hours if they do not review it. Students who cram before finals often pass the test but retain almost nothing a month later. The hours spent studying evaporate. Worse, the cycle repeats every semester.

Spaced repetition fixes this by scheduling reviews at the exact moments your memory starts to fade. Instead of reviewing everything the night before, you spread reviews across increasing intervals. Each review strengthens the memory trace and pushes the next forgetting point further into the future. The challenge is choosing the right schedule. This cheat sheet compares every major spaced repetition system so you can pick one and start today.

What Is Spaced Repetition?

Spaced repetition is a study technique that schedules review sessions at gradually increasing intervals. It is based on the forgetting curve, first documented by Hermann Ebbinghaus in 1885, which shows that memory decays exponentially after initial learning. By reviewing material just before you forget it, each session reinforces the memory and extends the time until the next review is needed. The result is long-term retention with less total study time than traditional methods.

Spaced Repetition Schedule Comparison Table

This is the core reference. Each row describes a different spaced repetition schedule, its exact intervals, and when to use it.

Quick Interval Summary

For a card learned on Day 0, here is when each system schedules the first five reviews:

The Leitner Box System

The Leitner system uses physical or virtual boxes numbered 1 through 5. Each box has a fixed review interval. All new cards start in Box 1.

How it works:

1. Box 1 — Review every day. All new and forgotten cards live here.
2. Box 2 — Review every 2 days. Cards move here after a correct answer in Box 1.
3. Box 3 — Review every 4 days.
4. Box 4 — Review every 8 days.
5. Box 5 — Review every 14 days. Cards here are well-learned.

Rules:

• Correct answer: card moves to the next box.
• Incorrect answer: card returns to Box 1, regardless of its current box.

Strengths: Simple to set up with index cards and a shoebox. No software needed. The system is forgiving because difficult cards cycle back to daily review automatically.

Weaknesses: Fixed intervals do not adapt to individual card difficulty. Cards in Box 5 have a maximum interval of 14 days, which is short for true long-term retention. Scaling beyond a few hundred cards becomes physically cumbersome.

SM-2 Algorithm (Anki Default)

SM-2 is the algorithm that powers Anki, the most widely used spaced repetition software. Developed by Piotr Wozniak for SuperMemo in 1987, it calculates intervals dynamically based on how well you recall each card.

Core concept: Easiness Factor (EF)

Every card starts with an EF of 2.5. After each review, you rate your recall on a scale from 0 to 5:

Interval calculation:

• First review: 1 day after learning
• Second review: 6 days after first review
• Subsequent reviews: previous interval multiplied by the card's EF

For a card with the default EF of 2.5, the schedule looks like this: Day 1, Day 6, Day 15, Day 38, Day 95, Day 238. Easy cards accelerate faster. Difficult cards get shorter intervals and more frequent reviews.

Strengths: Adapts to each card individually. Handles thousands of cards efficiently. Widely supported by free software.

Weaknesses: The rating scale is subjective. New users tend to over-rate their recall, which inflates intervals and causes forgetting. The algorithm does not account for card relationships or interference effects.

Simple Schedules for Exam Prep

Not everyone needs a full algorithm. If your exam is in one to two weeks, a fixed schedule is faster to set up and easier to follow.

The 2-3-5-7 Method

This schedule is designed for a two-week study window:

Start this method at least 17 days before your exam. If you have less time, compress the intervals but keep at least one day between sessions.

Day-Before-Exam Schedule

If you have 7 days or fewer, use this compressed plan:

This schedule is not ideal for long-term retention. It is a triage plan. The goal is to hold enough information in working memory to pass the test. For lasting knowledge, switch to a longer system after the exam.

How to Build Your Own Spaced Repetition Schedule

No single schedule fits every learner. Here is a practical framework for creating a custom plan.

Step 1: Start Simple

Begin with the Leitner system or the 2-3-5-7 method. Both are easy to follow without software. Use them for one to two weeks to build the habit of daily review.

Step 2: Track Your Recall Rate

After each review session, note how many cards you got right on the first try. Aim for a recall rate between 85 and 90 percent. This range means the intervals are challenging enough to strengthen memory but not so long that you forget.

Step 3: Increase Intervals Gradually

When a card feels automatic, extend its interval. A good rule is to multiply the current interval by 2 to 2.5 after each successful review. If you forget, reset the card to a short interval and rebuild.

Step 4: Use Software When You Outgrow Manual Methods

Once you manage more than 200 cards, manual scheduling becomes a burden. Switch to Anki or a similar tool. Import your existing cards and let the algorithm handle scheduling. You can still override intervals for specific cards.

Common Mistakes to Avoid

Best Tools for Spaced Repetition

If your study materials are handwritten notes, textbook photos, or lecture slides, Pixno (opens in a new tab) can convert them into structured digital text — ready to import into any flashcard app for spaced repetition review. This eliminates the time-consuming step of manually typing out card content from physical materials.

Frequently Asked Questions

What is the best spaced repetition schedule for exams?

For short-term exam prep (one to two weeks), the 2-3-5-7 method works well because it fits neatly into a study window. For longer preparation periods (one month or more), the Leitner Box system or Anki's SM-2 algorithm provides stronger long-term retention by adjusting intervals based on how well you recall each card.

How many flashcards per day should I review with spaced repetition?

Most learners do well with 20 to 30 new cards per day and all due reviews. Anki's default is 20 new cards daily. Going above 50 new cards per day leads to review pile-ups within a week. Start with 10 to 15 new cards if you are new to spaced repetition and increase once the daily review load feels manageable.

Does spaced repetition actually work?

Yes. Spaced repetition is one of the most validated techniques in cognitive science. A 2006 meta-analysis by Cepeda et al. across 254 studies confirmed that distributed practice produces significantly better retention than massed practice (cramming). Medical students using Anki have reported exam score improvements of 10 to 20 percent compared to traditional study methods.

What is the difference between the Leitner system and SM-2?

The Leitner system uses fixed box-based intervals (such as 1, 2, 4, 8, and 14 days) and moves cards forward or backward depending on correct or incorrect answers. SM-2, the algorithm behind Anki, calculates intervals dynamically using an easiness factor that adjusts per card based on your self-rated recall quality. SM-2 is more precise but requires software; Leitner works with physical flashcards.

How long does spaced repetition take to show results?

Most learners notice improved recall within two to three weeks of consistent daily reviews. Research shows that the biggest retention gains appear after the first three to four review cycles. For exam preparation, starting spaced repetition at least three weeks before the test date gives enough time for multiple review intervals to take effect.

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