Blunder
"A very bad move that loses significant material or the game, usually marked as ?? in chess notation."
In-Depth Explanation
A blunder is a serious mistake — far worse than an inaccuracy (?) or a mistake (?). In engine analysis, blunders often drop evaluation by a full point or more (e.g. from +1.0 to -2.0). Common blunder causes include hanging pieces, missing checks, overlooking forks, and time trouble. Reviewing blunders with Stockfish is one of the fastest ways to improve.
Recommended Tools
Frequently Asked Questions
Different platforms use different thresholds, but a large evaluation drop (often 2+ pawns) is typically labeled a blunder. Use our Stockfish Output Explainer to interpret engine scores.
Before every move, check for opponent threats (checks, captures, attacks). Analyze your games after each session and tag recurring blunder patterns.
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