Forgetting Curve Calculator
Calculate memory retention decay over time using the Ebbinghaus forgetting curve formula.
Memory Parameters
Higher = slower forgetting (1 is average)
Ebbinghaus Formula
R = R0 x e^(-t/S)
R = retention, R0 = initial, t = time, S = stability
Retention After 7 Days
0.1%
Lost 99.9% of original memory
Memory Half-Life
0.7 days
Optimal Review
0.2 days
Target Reached
0.2 days
Retention Lost
99.9%
Retention Over Time
Day 0
100.0%
Day 1
36.8%
Day 2
13.5%
Day 3
5.0%
Day 4
1.8%
Day 5
0.7%
Day 6
0.2%
Day 7
0.1%
Understanding the Forgetting Curve
Hermann Ebbinghaus
In 1885, Ebbinghaus discovered that memory decays exponentially. Without review, we forget ~50% within an hour and ~70% within 24 hours.
Fighting the Curve
Each review at the optimal time increases memory stability, making future forgetting slower. This is the basis of spaced repetition systems.
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