Spaced-repetition tools do not all use the same scheduler. Modern Anki supports both its legacy SM-2-based scheduler and FSRS. Mnestica does not run Anki or FSRS: its flashcard scheduler is a smaller, SM-2-inspired implementation with explicit rules you can inspect below.

The three stored values

Each Mnestica flashcard has an interval, an ease factor, and a due date. The interval is the whole number of days until the next review. The ease factor is a multiplier used for successful reviews. The due date is the current time plus the selected interval.

New cards begin with interval zero and ease factor 2.5. For a new card, Mnestica schedules Forgot for the same day in a later session, Hard for one day later, Good for two days later, and Easy for three days later. Forgot does not reinsert the card into the current session.

What the four ratings do

After the learning phase, Mnestica applies these rules:

  • Forgot: reset the interval and SRS level to zero; reduce ease by 0.20.
  • Hard: multiply the interval by 1.2; reduce ease by 0.15.
  • Good: multiply the interval by the current ease; leave ease unchanged.
  • Easy: multiply the interval by the updated ease and then by 1.3; increase ease by 0.15.

Intervals are rounded to whole days, kept in Hard < Good < Easy order, and capped at 36,500 days. Ease is always clamped between 1.3 and 2.5, so an Easy rating cannot raise it above 2.5.

A worked example

Suppose a card has a three-day interval and an ease factor of 2.5. An Easy rating produces:

3 × 2.5 × 1.3 = 9.75

Mnestica rounds that to a ten-day interval. The attempted ease increase is clamped, so the stored ease remains 2.5 rather than becoming 2.65.

If the next rating is Hard, the interval becomes 10 × 1.2 = 12 days and the ease falls to 2.35. A Forgot rating after that resets the interval to zero and reduces ease to 2.15.

What the broader Memory Studio view shows

Memory Studio combines stored scheduling and practice events to order cards, notes, and reading items. It shows due workload, queue composition, and care cases so learners can decide what to review or repair next. It does not present a measured probability that a learner will remember something or proof of long-term retention.

Rate the review that happened

The scheduler can only react to the rating you choose. Forgot means no recall; Hard means recall required substantial effort; Good means ordinary successful recall; Easy means the answer was immediate. Those labels are inputs to the next-date calculation, not grades or guarantees about a future outcome.

When a card itself is the problem, use Fix card. You can edit the question or answer directly. When review evidence supports a repair, Mnestica can also show a rewrite, split, suspension, or retirement suggestion and applies it only after you approve it.