View Source Anki Algorithm for Review Cards
From Anki Algorithm Explained in 5 minutes!
Default starting ease: 250% Default interval modifier: 100% Default hard interval: 120% Default easy bonus: 130%
Press <again>: Go through lapse steps, then new interval becomes % of old interval AND subtract 20% from ease
Press <hard>: new_interval = current_interval 1.2 (default hard interval) 1 (default interval modifier) AND subtract 15% from ease
Press <good>: new_interval = current_interval 2.5 (ease%) 1 (default interval modifier) AND keep ease unchanged
Press <easy>: new_interval = current_interval 2.5 (ease%) 1 (default interval modifier) * 1.3 (default easy bonus) AND add 15% to ease
Anki algorithm only applies to graduated (review) cards, not cards in the learning phase
The Anki scheduler is in anki/pylib/anki/scheduler/v2.py