Mate in 1
Benchmark page
Grok 4.20 scored 54.7% strict accuracy on ChessBench, solving 82 of 150 fixed Lichess tactics when the answer had to match the expected UCI move line exactly.
Strict accuracy
54.7%
Correct puzzles
82 / 150
Prompt tokens
79,371
Total cost
$4.28
Benchmark updated
May 31, 2026, 6:23 AM
Find the tactical line that creates a fork.
Find the line that wins an undefended piece.
Solve a forced mate in one move.
Solve a forced mate in two moves.
Find the tactical line that exploits a pin.
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It also links back to the benchmark methodology and exposes model-specific copy, numbers, and sample puzzle outcomes that are relevant to searches like "Grok 4.20chess benchmark" and "Grok 4.20tactical reasoning results".
For the full dataset definition and scoring details, visit the ChessBench dataset and methodology page.
These examples add readable, model-specific context beyond a single leaderboard number.
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Expected line: d6h6
Model line: No parseable line returned
Parse status: invalid_count