Free tool

Retention Curve Simulator

Ebbinghaus's forgetting curve shows retention dropping fast after you first learn something. Toggle between cramming and spaced review to see why a review at the right moment resets the curve instead of just adding more reading.

Review days: 1, 3, 7, 14, 30

Encodr schedules those review points for you automatically, so retention never gets the chance to fall off the curve.

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What the curve is actually showing

Hermann Ebbinghaus measured his own memory in the 1880s and found retention decays roughly exponentially after learning something new: steep in the first day, then leveling off. Cramming studies material once and lets it decay along that single curve. Spaced review instead reviews right as retention is fading - here, at day 1, 3, 7, 14, and 30 - and each review resets retention back up and flattens the decay that follows, because the memory is stronger each time it's successfully retrieved. That's the entire mechanism behind spaced repetition: not more total study time, just better-timed study time.

From the blog

What spaced repetition actually does

The idea is old, simple, and almost always explained badly.

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Cramming vs. spacing: what the research actually says

Cramming isn't irrational. It optimises for the wrong exam.

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Why you should review new material within 24 hours

The steepest part of the forgetting curve happens in the first day, not the first week.

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