FSRS in Deckbase

FSRS (Free Spaced Repetition Scheduler) is an open-source spaced repetition algorithm created by Jarrett Ye. It models your memory for each card using three values:

• Difficulty (D) — how hard the card is for you.
• Stability (S) — how long the memory lasts.
• Retrievability (R) — the current probability you will recall it correctly.

FSRS schedules each review so that Retrievability is near your chosen retention target when the card appears again. This usually produces fewer unnecessary reviews than older fixed-heuristic schedulers like SM-2.

FSRS is the default and only scheduler in Deckbase. You do not need to enable it or tune parameters. Every review you complete feeds back into the model, and future intervals are calculated automatically.

When you create or import cards, Deckbase starts with default FSRS parameters. As you accumulate reviews, the scheduler learns your personal retention patterns and adjusts intervals accordingly.

Retention target

The retention target is the probability that you will correctly recall a card when it is shown again. Deckbase defaults to a target in the 90–92% range, which is a practical balance between recall and daily workload for most learners.

You can adjust your target in Deck settings. We recommend changing it by only 1–2 points at a time and waiting at least two weeks before adjusting again.

Daily workflow

1. 1

   Open your deck and review all due cards in one session.

2. 2

   Rate each card honestly. Overrating hard recalls leads to intervals that are too long.

3. 3

   Add new cards only at a rate you can sustain. A large backlog is usually a sign that new-card intake is too high.

4. 4

   Check your weekly stats to see completion rate, average session length, and lapse trends.

Importing from Anki

Deckbase supports APKG import, so you can bring existing Anki decks over. Your cards, notes, and media transfer; review history and scheduling data do not. After import, cards start fresh with FSRS intervals.

If you are switching from Anki's SM-2 scheduler, expect a short adjustment period. FSRS may schedule mature cards sooner or later than SM-2 would have, depending on your personal retention patterns.

FSRS works the same way on mobile as it does on the web. Your retention target, card schedules, and review history sync across devices, so you can review on your phone and pick up later on your laptop without losing progress.

• Offline reviews — cards you review without an internet connection are saved locally and synced the next time you are online.
• Due notifications — enable push reminders to keep your daily review streak without opening the app manually.
• Same retention target — your target applies everywhere; mobile sessions count the same as web sessions.
• Short sessions — mobile reviews work best in 5–10 minute chunks. Rate honestly even when tapping quickly.

If your intervals feel too long or too short on mobile, the cause is usually rating behavior, not the device. Avoid tapping "Good" for answers you barely remembered — inconsistent ratings make FSRS less accurate on every platform.

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