# Anki Algorithm for Review Cards

From [Anki Algorithm Explained in 5 minutes!](https://www.youtube.com/watch?v=newlu_xQazU&t=289s)

## Ease Factors

- Default starting ease: 250%
- Default interval modifier: 100%
- Default hard interval: 120%
- Default easy bonus: 130%

## Responses

- 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


The Anki algorithm as described herein only applies to graduated (review) cards, not cards in the learning phase.

## Anki Scheduler 

The Anki scheduler is in [`anki/pylib/anki/scheduler/v2.py`](https://github.com/ankitects/anki/blob/main/pylib/anki/scheduler/v2.py).