Flashcard Review Interval Calculator

The SM-2 algorithm (used by Anki and SuperMemo) calculates optimal review intervals based on how well you recalled each card. Rate your recall 0–5 and this tool tells you exactly when to review next for maximum long-term retention.

Card / Topic Name

Current Interval (days since last review)

Easiness Factor (default 2.5)

How well did you recall? (0 = blank, 5 = perfect)

Blank

Wrong

Hard

Good

Easy

How SM-2 Works

The new interval = old interval × easiness factor. Your EF adjusts based on recall quality: a perfect (5) increases it slightly; a hard (2) decreases it. Cards rated below 3 reset to day 1. Over time, easy cards space out to months; hard cards repeat frequently.