Method
How BlunderLoop grades your chess
The rules behind every report, written down. Each page states its answer up front and matches the exact thresholds in the analysis code.
Analysis Policy v1: Engine, Budgets, and Thresholds
The fixed rules behind every BlunderLoop report: Stockfish 18 lite in your browser, per-device time budgets, and the v1 win-chance thresholds.
What Makes a Chess Move a Blunder?
How BlunderLoop grades every move — best, inaccuracy, mistake, or blunder — by win-chance drop instead of raw centipawn loss.