Spaced repetition scheduler
Replay a card review log with SM-2 or FSRS and see when every card is due, what its interval is, and which cards have become leeches.
About this tool
Paste a flashcard review log and this tool replays each card's history to compute the next review date. It is designed for quick schedule audits: no account, no deck database, and no hidden state. Each run is deterministic, so the same rows and options produce the same due dates.
Use one row per review with a card name, a date, and a grade:
card, date, grade
capital-of-peru, 2026-08-01, good
capital-of-peru, 2026-08-02, good
capital-of-peru, 2026-08-08, good
kanji-water, 2026-08-01, again
kanji-water, 2026-08-02, hard
Rows may be comma, tab, semicolon, pipe, or whitespace separated. Grades can be words (again, hard, good, easy), four-button numbers (1–4), or SuperMemo quality scores (0–5). A line containing only a card name declares an unreviewed card so it appears as new and due.
Worked example
With SM-2 defaults and today = 2026-08-24, this input:
card, date, grade
capital-of-peru, 2026-08-01, good
capital-of-peru, 2026-08-02, good
capital-of-peru, 2026-08-08, good
kanji-water, 2026-08-01, again
kanji-water, 2026-08-02, good
new-card-never-seen
produces a schedule table with each card's next due date, interval, days until due, repetition count, lapse count, and status. Use output = csv for spreadsheets, output = json for scripts, output = explain to see every state transition, or output = forecast to project the next reviews assuming the selected forecast grade.
Limits and edge cases
- The run is capped at 5,000 review rows and 2,000 distinct cards.
todayis explicit. When it is blank, the latest review date in the log is used rather than the system clock.- FSRS mode exposes difficulty, stability, and retrievability, and accepts a custom 21-number weight vector. It does not train or optimise weights from your history.
- There is no interval fuzz or workload balancing. This keeps output reproducible, but a real flashcard app may spread cards differently.
- Dates must be calendar dates in
YYYY-MM-DDform./and.separators are accepted, but ambiguous regional dates are not.
FAQ
Which algorithm should I choose?
Choose sm2 when you want the classic repetition/ease/interval model used by many simple flashcard schedulers. Choose fsrs when you want difficulty, stability, retrievability, and desired-retention controls. FSRS output is useful for comparing how the same history would schedule under a memory-model approach.
Can this import a full flashcard collection?
It imports a review log, not card fronts, answers, tags, or media. Export the columns you need as text or CSV: card identifier, review date, and grade. Optional state fields such as ease=, interval=, reps=, lapses=, difficulty=, stability=, and last= can be added to seed existing scheduler state.
Why do my dates differ from a flashcard app?
Apps often add interval fuzz, daily load balancing, buried siblings, deck limits, timezone rules, and version-specific scheduler tweaks. This tool intentionally computes a deterministic per-card schedule from the pasted history and parameters. Use the output as an auditable calculation, not as a full deck-sync replacement.
Does the tool train FSRS weights?
No. Training FSRS weights requires optimisation over a large history and is out of scope for a synchronous browser-local calculator. Paste a 21-number vector if you already have one; otherwise the built-in defaults are used.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool spaced-repetition-scheduler "capital-of-peru, 2026-08-01, good
capital-of-peru, 2026-08-02, good
kanji-water, 2026-08-02, again"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/spaced-repetition-scheduler/?reviews=capital-of-peru%2C%202026-08-01%2C%20good%0Acapital-of-peru%2C%202026-08-02%2C%20good%0Akanji-water%2C%202026-08-02%2C%20again&algorithm=sm2&grade_scale=auto&today=2026-08-24%20%28blank%20%3D%20last%20review%20in%20the%20log%29&output=table&sort=due&only_due=true&desired_retention=0.9&ease_start=2.5&min_ease=1.3&first_interval=1&second_interval=6&easy_bonus=1.3&hard_multiplier=1.2&interval_modifier=1.0&max_interval=36500&forecast_reviews=6&forecast_grade=good&fsrs_weights=0.2172%2C%201.1771%2C%203.2602%2C%20%E2%80%A6%20%2821%20numbers%2C%20blank%20%3D%20built-in%29Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.