What the curve shows
The dashed line is what happens if you study a topic once and never come back to it. The solid line includes the reviews you have switched on. Each review lifts recall back up and makes the next drop slower.
The model uses the same shape of forgetting curve as FSRS, an open-source scheduler used by flashcard apps. The numbers are made up but plausible. Treat it as a picture of the idea, not a prediction of your exam score.
Where the forgetting curve comes from
In the 1880s Hermann Ebbinghaus memorised lists of nonsense syllables, then measured how much quicker it was to relearn them after different delays. He called the time saved 'savings'. His own figures are below.
Savings are not the same as the percentage you could recall, and nonsense syllables are much harder to keep than ideas you understand. The pattern still holds for real material: a steep drop at first, then a slower one.
Questions
How often should I review a topic?
A simple pattern is about a day after first learning it, then a few days later, then a week, then a couple of weeks. The spaced repetition planner on this site builds that schedule for a list of topics.
Is the forgetting curve the same for everyone?
No. How fast you forget depends on how well you understood the material, how it connects to what you already know, sleep, and how you reviewed it. Testing yourself slows forgetting more than re-reading.
What counts as a review?
Actively recalling the material: doing questions, flashcards, or writing down what you remember before checking. Re-reading your notes helps much less.
Other free tools
- Revision timerFocused blocks with a recall check at every break, so the break does some work too.
- Marks needed calculatorEnter the papers you have sat and the grade boundary you are aiming for. See what you need on the rest.
- Spaced repetition plannerType your topics and exam date. Get a day-by-day revision plan with reviews spaced out.
Need something to revise from? Browse the free study guides or turn your own notes into flashcards.