How Spaced Repetition Works
Memory Lab adjusts the review schedule of each note based on how you rate it. Click Easy or Hard below to see how the schedule changes.
The interval
The interval is the number of days before a note comes back for review. It starts at 1 day and grows after each review. Choosing Easy on a note you know well makes it come back far less often. Choosing Hard keeps it coming back frequently until it sticks.
The ease factor
Every note has an ease factor - a number that tracks how well you know it. It starts at 2.5 (the maximum). Each Easy rating nudges it up by 0.10; each Hard rating nudges it down by 0.15, with a floor of 1.3. A note you consistently find Easy maintains a high ease factor and comes back less and less often. A note you find Hard drifts toward 1.3, where the gap between reviews barely grows. The system keeps returning it until it sticks.
Easy vs Hard
| Easy | Hard | |
|---|---|---|
| Interval multiplier | × ease factor | × 1.0 by default, adjustable between 0.5–1.0 |
| Ease factor change | +0.10 | −0.15 |
| Growth rate | Aggressive | Conservative |
Tips
- A new note always starts with a 1-day interval. It will appear the next day regardless of how easy it feels.
- Consistent Easy ratings compound fast: 1 day → 3 → 8 → 20 → 50 days with a 2.5 ease factor.
- Consistent Hard ratings keep the ease factor low, so the note returns frequently. This is by design - the system treats it as something that still needs more practice.
- The ease factor is per note. A note you find difficult won't affect the schedule of any other note in your library.