Work out flashcard review interval instantly with clear inputs, formula shown and shareable results.
This follows the SM-2 rule: the ease factor is adjusted by 0.1 - (5 - q) x (0.08 + (5 - q) x 0.02), and the next interval is the current interval times the updated ease, or reset to one day if recall scored below 3. Spacing reviews just before forgetting is what makes flashcards efficient, and SM-2 automates that by letting each card's own difficulty set its schedule.
Ease update
new ease = ease + 0.1 - (5 - quality) x (0.08 + (5 - quality) x 0.02), clamped to 1.3 - 3.0
Next interval
next interval = current interval x new ease, or 1 day when quality < 3
new ease = ease + 0.1 - (5 - quality) x (0.08 + (5 - quality) x 0.02), clamped to 1.3 - 3.0. This follows the SM-2 rule: the ease factor is adjusted by 0.1 - (5 - q) x (0.08 + (5 - q) x 0.02), and the next interval is the current interval times the updated ease, or reset to one day if recall scored below 3.
Spacing reviews just before forgetting is what makes flashcards efficient, and SM-2 automates that by letting each card's own difficulty set its schedule.
Enter current interval, ease factor, recall quality (0 blank - 5 perfect). The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.