Blunders get more expensive the longer a game runs. Across 340,171 analysed games containing a move that cost at least 200 centipawns, the typical player's worst move costs 451 centipawns when it falls in the first fifth of the game and 822 when it falls in the last, rising at every step in between.

Blunders get more expensive the longer a game runs.

Across 340,171 analysed games containing a move that cost at least 200 centipawns, the typical player's worst move costs 451 centipawns when it falls in the first fifth of the game and 822 when it falls in the last, rising at every step in between.

Split each game into fifths by move number and the average cost of its worst move climbs 451, 467, 519, 583, 822 centipawns. Each figure is the median across players rather than the corpus average, so the trend belongs to players and not to whoever uploaded the most games. Late mistakes are not merely more frequent because games are long; they are worse when they happen.

Across 340,171 analysed games from 225 players.

The Position

Sindarov, Javokhir beat Van Foreest, Jorden at GCT: Sinquefield Cup 2026.

White to move.

The final position is below.

The answer runs in tomorrow's issue.

Lichess Broadcasts

The Opening Files · No. 2

The piece most likely to play your worst move is the queen.

Across 289,300 analysed games it is the biggest single source of blunders for 72 of 223 players, ahead of the knight at 67, and accounts for 19.8% of the typical player's blunders.

Every game counted here contains a move that cost at least 300 centipawns, grouped by the piece that moved rather than by the move's notation. That distinction is the whole point: castling looks like the top blunder when moves are counted by name, because it is the one move with a symbol of its own, yet it is the worst piece for 0 players and 1.4% of a typical player's mistakes.

Across 289,300 analysed games from 223 players.

The Opening Files runs again tomorrow.