How to Change Your Study Algorithm (FSRS, SM-2, Leitner)

Nebulearn runs FSRS by default. You can switch to SM-2 (classic Anki style) or Leitner (numbered boxes) without leaving the app.

Deep dive on what each algorithm does: blog explainer.

Change algorithm

1. Open Settings.
2. Go to Study Preferences.
3. Under Learning Algorithm, pick FSRS, SM-2, or Leitner.
4. Save.

Your cards keep their history. You're not starting from zero.

Which to pick

Algorithm	Pick if...
FSRS	You're new, or you want best retention per minute (default)
SM-2	You're coming from classic Anki and want familiar ease-factor behavior
Leitner	You want simple boxes (daily, 3-day, weekly) you can explain in 30 seconds

Most people should stay on FSRS unless something feels wrong after a few weeks.

Tune FSRS

In Study Preferences → FSRS:

• Desired retention (e.g. 90%): higher = more reviews, fewer lapses
• Maximum interval: cap how long between reviews
• Learning / relearning steps: minute-based steps for new cards

Default FSRS settings work for most classes. Touch these if reviews feel too easy or too punishing.

Tune SM-2

• Interval modifier: scale all intervals up/down
• Ease bonus / hard interval: how ratings affect spacing
• Maximum interval: upper cap

Tune Leitner

• Box intervals: days between each box (default 1, 3, 7, 14, 30, 60, 120)
• Maximum interval: cap for top box

Shrink early boxes before a cram-heavy exam block. Stretch them for long-term retention.

Reset to defaults

Each algorithm has a Reset in Settings if you messed up tuning and want factory defaults back.

After switching

Give it one week of daily reviews before you judge. Algorithm changes feel subtle until the queue reshapes.

New to spaced repetition? Start with how to study with spaced repetition.