Reading _nextRevIvl
and its subfunction _constrainedIvl
plus _rescheduleLapse
will illuminate how Anki calculates the due date (the “interval”) of a flashcard, based on whether you answer
- 1 (fail)
- 2 (pass but hard)
- 3 (pass)
- 4 (pass and easy)
This is more of a self-note, so I assume you’ve read the Anki manual top-to-bottom a couple of times.
Let d >= 0
, “delay”, be the days between the due date and the date you actually reviewed. This can be important because if you successfully answer a flashcard a long time after it was due for study, that means you probably know it really well.