--- title: "Blunder check in chess" url: "https://georgelichess.com/glossary/blunder-check.md" canonical_url: "https://georgelichess.com/glossary/blunder-check" last_updated: "2026-11-07" type: "reference" summary: "A blunder check is a quick test, made by a person before moving or by software afterward, that looks for a move which hangs material." related: ["https://georgelichess.com/glossary/blunder.md", "https://georgelichess.com/glossary/hanging-piece.md", "https://georgelichess.com/glossary/loose-piece.md", "https://georgelichess.com/glossary/blunder-check-habit.md", "https://georgelichess.com/glossary/candidate-moves.md", "https://georgelichess.com/glossary/category/computer-chess.md", "https://georgelichess.com/glossary.md"] --- # Blunder check in chess > **For AI agents:** the complete index of GeorgeLiChess pages is [llms.txt](https://georgelichess.com/llms.txt). Every page is also served as markdown at its URL plus .md. A blunder check is a quick test, made by a person before moving or by software afterward, that looks for a move which hangs material. A blunder check is a quick test, made by a person before moving or by software afterward, that looks for a move which hangs material, allows a tactic or loses the game outright. A [blunder](https://georgelichess.com/glossary/blunder.md) check works in two settings. Over the board, it is a short pause before you release a piece: you ask what the move leaves undefended, what checks and [captures](https://georgelichess.com/glossary/capture.md) your opponent now has, and whether the piece you are moving was guarding something. After the game, a software blunder check scans your moves and flags the ones where the [evaluation](https://georgelichess.com/glossary/evaluation.md) fell sharply. The over-the-board version is the more valuable skill, because most club games are decided by one oversight rather than by deep strategy. A common [mistake](https://georgelichess.com/glossary/mistake.md) is checking only your own plan and never asking what the opponent's last move threatens. Another is skipping the check when the move feels obvious, which is exactly when a recapture, a pinned piece or a back-rank problem slips through. A practical habit is a fixed routine: look at every check, capture and threat for the opponent after your intended move, then play. Keep it brief enough to repeat every move. Software tools differ in how big a drop counts as a blunder, so treat their labels as a guide rather than a verdict. Also called: blunder check tool. Compare it with [Blunder check habit](https://georgelichess.com/glossary/blunder-check-habit.md). A blunder check habit is a short, fixed routine run before every move, asking what the opponent threatens and whether the intended move leaves anything undefended, to catch one-move oversights. Also worth reading is [Fair play](https://georgelichess.com/glossary/fair-play.md). Fair play is the rule that every game must be decided by the players' own thinking, which means no engine help, no advice from others during play and no tricks that distort a result. A neighboring idea is [Premove](https://georgelichess.com/glossary/premove.md). A premove is a move entered on an online board before the opponent has replied, which is played automatically as soon as it becomes your turn if it is still legal. An engine can tell you what "Blunder check" means for a position, but not which mistakes you keep making; a [first lesson](https://georgelichess.com/book/first-lesson.md) with George Li reviews your games and finds those. ## Related terms - [Blunder](https://georgelichess.com/glossary/blunder.md) - [Hanging piece](https://georgelichess.com/glossary/hanging-piece.md) - [Loose piece](https://georgelichess.com/glossary/loose-piece.md) - [Blunder check habit](https://georgelichess.com/glossary/blunder-check-habit.md) - [Candidate moves](https://georgelichess.com/glossary/candidate-moves.md) ## Guides that go further - [How to choose a chess coach](https://georgelichess.com/how-to-choose-a-chess-coach.md): What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid. - [How much does chess coaching cost?](https://georgelichess.com/chess-coaching-cost.md): Published rates for private, group and subscription chess coaching, with the source and the date of each. - [The first lesson](https://georgelichess.com/book/first-lesson.md): A game review, a read on your level and a written study plan from George Li. [Book your first lesson](https://georgelichess.com/book.md) and George Li reviews your games and builds a study plan around them. Questions about lessons: write to hello@georgelichess.com. ## Related - [Blunder in chess](https://georgelichess.com/glossary/blunder.md) - [Hanging piece in chess](https://georgelichess.com/glossary/hanging-piece.md) - [Loose piece in chess](https://georgelichess.com/glossary/loose-piece.md) - [Blunder check habit in chess](https://georgelichess.com/glossary/blunder-check-habit.md) - [Candidate moves in chess](https://georgelichess.com/glossary/candidate-moves.md) - [Chess terms: Computer chess and analysis](https://georgelichess.com/glossary/category/computer-chess.md) - [Chess terms glossary: plain definitions](https://georgelichess.com/glossary.md)