FSRS is the most significant improvement to Anki in years. Here's what it is, why it's better than SM-2, how to enable it, and what to set your retention target to.
FSRS (Free Spaced Repetition Scheduler) is a new scheduling algorithm built into Anki that replaces the old SM-2 algorithm. It's based on a modern memory model, learns from your individual review history, and requires fewer reviews to achieve the same retention rate — typically 15–20% fewer reviews.
FSRS is based on the DSR (Difficulty, Stability, Retrievability) model of memory. Three variables govern every card:
How intrinsically hard is this card? Some cards are just harder to remember than others — different content, different connections, different personal relevance. FSRS tracks this per-card rather than applying a one-size-fits-all ease factor.
How long until you forget this card? Stability increases each time you successfully recall it. A card you've reviewed 10 times has much higher stability than one you've reviewed twice. FSRS uses this to schedule reviews at the optimal moment.
What is the probability you can recall this card right now? This decays over time following a forgetting curve. FSRS shows you the card when R drops to your target retention level (e.g., 90%). That's the optimal review moment — not too early (wasting a review), not too late (after forgetting).
Requires Anki 23.10 or later. Update Anki first if needed.
| Retention | Reviews per day | Best for |
|---|---|---|
| 0.70 | Very low | Language learning, low-stakes content |
| 0.80 | Low | General studying, moderate importance |
| 0.90 | Moderate (recommended default) | Most learners — good balance |
| 0.95 | High | Medical school boards, high-stakes exams |
| 0.97+ | Very high | Not recommended — exponentially more reviews for marginal gain |
Note: Going from 90% to 95% retention roughly doubles your daily review count. Going to 97% quadruples it. The marginal benefit of each additional percentage point decreases while the cost increases sharply. 90% is the sweet spot for most learners.
The FSRS4Anki Helper add-on (code: 759844606) adds a full control panel for FSRS management. It lets you:
Related: Anki settings complete guide, spaced repetition schedule explained, what is spaced repetition.
Now that your FSRS settings are optimized, fill your deck. StudyCards AI generates properly structured flashcards from your notes and exports them directly to Anki — ready for FSRS scheduling from card one.
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