Claude Opus 5.5
Anthropic · released 2026-09-22 · route claude-opus-5-5 · Model profile
Opening gap: +205 (95%: -25 to +436). The interval includes zero, so we can't yet say whether it performs differently across the variants.
Standard
- Rating
- 1,46395%: 1,299 to 1,627
- Record
- 11 won, 3 drawn, 10 lost of 24
- Accuracy (open positions)
- 88.7
- Accuracy (all moves)
- 89.9
- Average centipawn loss
- 52
- Blunders / mistakes / inaccuracies per 100 moves
- 4.8 / 2.6 / 8.0
- Matched Stockfish's first choice
- 36%
- In Stockfish's top three
- 65%
- Legal on the first try
- 95.9%
- Illegal / invalid
- 39 of 972 answers
- Forfeits
- 0
- Adjudicated games
- 17
- API-equivalent cost per game
- $0.917
- API-equivalent cost per move
- $0.024
- Seconds per move
- 11.3
- Model minutes per game
- 7.3
- Tokens per move (in / out)
- 1,079 / 748
- Reasoning tokens per move
- 594
- Aborted on our side (not counted)
- 2
By phase
| Phase | Moves | Accuracy | Centipawn loss | Blunders /100 | Engine match |
|---|---|---|---|---|---|
| Opening | 240 | 92.5 | 28 | 2.5 | 49% |
| Middlegame | 343 | 85.9 | 57 | 6.1 | 36% |
| Endgame | 350 | 88.1 | 63 | 5.1 | 26% |
Chess960
- Rating
- 1,25895%: 1,095 to 1,420
- Record
- 12 won, 0 drawn, 12 lost of 24
- Accuracy (open positions)
- 81.2
- Accuracy (all moves)
- 84.3
- Average centipawn loss
- 81
- Blunders / mistakes / inaccuracies per 100 moves
- 10.0 / 5.3 / 12.1
- Matched Stockfish's first choice
- 31%
- In Stockfish's top three
- 58%
- Legal on the first try
- 94.8%
- Illegal / invalid
- 39 of 790 answers
- Forfeits
- 0
- Adjudicated games
- 19
- API-equivalent cost per game
- $0.903
- API-equivalent cost per move
- $0.029
- Seconds per move
- 14.0
- Model minutes per game
- 7.3
- Tokens per move (in / out)
- 1,115 / 997
- Reasoning tokens per move
- 828
- Aborted on our side (not counted)
- 0
By phase
| Phase | Moves | Accuracy | Centipawn loss | Blunders /100 | Engine match |
|---|---|---|---|---|---|
| Opening | 240 | 82.3 | 60 | 9.6 | 24% |
| Middlegame | 334 | 77.3 | 100 | 12.9 | 33% |
| Endgame | 177 | 86.7 | 74 | 5.1 | 39% |
Games
Standard as blackWon vs Skill 0, 10% random moves44 plies · adjudicated: decisive advantage · $0.386Chess960 as blackWon vs Skill 0, 10% random moves58 plies · adjudicated: decisive advantage · $0.858Standard as whiteLost vs Stockfish Skill 463 plies · adjudicated: decisive advantage · $0.780Chess960 as whiteLost vs Stockfish Skill 235 plies · adjudicated: decisive advantage · $0.478Standard as blackLost vs Stockfish 150069 plies · checkmate · $0.620Chess960 as blackLost vs Stockfish 132051 plies · checkmate · $0.597Standard as whiteWon vs Stockfish 132061 plies · adjudicated: decisive advantage · $0.487Chess960 as whiteLost vs Skill 0, 10% random moves82 plies · checkmate · $1.14Standard as blackLost vs Stockfish 1700126 plies · adjudicated: decisive advantage · $1.48Chess960 as blackLost vs Stockfish 1500116 plies · adjudicated: decisive advantage · $1.80Standard as whiteLost vs Stockfish 150046 plies · checkmate · $0.497Chess960 as whiteLost vs Stockfish Skill 053 plies · adjudicated: decisive advantage · $0.783Standard as blackWon vs Stockfish 132052 plies · adjudicated: decisive advantage · $0.489Chess960 as blackWon vs Skill 0, 10% random moves48 plies · adjudicated: decisive advantage · $0.613Standard as whiteLost vs Stockfish Skill 468 plies · checkmate · $0.784Chess960 as whiteWon vs Stockfish Skill 239 plies · adjudicated: decisive advantage · $0.351Standard as blackDrew vs Stockfish 1500120 plies · adjudicated: dead level · $1.52Chess960 as blackLost vs Stockfish 1320150 plies · adjudicated: decisive advantage · $2.15Standard as whiteWon vs Stockfish 1320119 plies · adjudicated: decisive advantage · $1.36Chess960 as whiteWon vs Skill 0, 10% random moves117 plies · adjudicated: decisive advantage · $1.41Standard as blackLost vs Stockfish 170050 plies · adjudicated: decisive advantage · $0.550Chess960 as blackLost vs Stockfish 150066 plies · adjudicated: decisive advantage · $1.46Standard as whiteLost vs Stockfish Skill 2107 plies · adjudicated: decisive advantage · $1.42Chess960 as whiteLost vs Stockfish Skill 037 plies · adjudicated: decisive advantage · $0.665Standard as blackDrew vs Stockfish 1320122 plies · adjudicated: dead level · $1.60Chess960 as blackWon vs Skill 0, 10% random moves64 plies · adjudicated: decisive advantage · $1.04Standard as whiteDrew vs Stockfish Skill 4105 plies · threefold repetition · $1.67Chess960 as whiteLost vs Stockfish 170034 plies · checkmate · $0.541Standard as blackWon vs Stockfish 150098 plies · adjudicated: decisive advantage · $1.09Chess960 as blackWon vs Stockfish 132082 plies · adjudicated: decisive advantage · $1.05Standard as whiteWon vs Stockfish 132061 plies · adjudicated: decisive advantage · $0.640Chess960 as whiteWon vs Skill 0, 10% random moves43 plies · adjudicated: decisive advantage · $0.641Standard as blackLost vs Stockfish 1700100 plies · adjudicated: decisive advantage · $1.42Chess960 as blackWon vs Stockfish Skill 068 plies · adjudicated: decisive advantage · $1.02Standard as whiteWon vs Stockfish Skill 055 plies · checkmate · $0.582Chess960 as whiteWon vs Skill 0, 10% random moves33 plies · adjudicated: decisive advantage · $0.395Standard as blackWon vs Skill 0, 10% random moves34 plies · adjudicated: decisive advantage · $0.299Chess960 as blackWon vs Skill 0, 25% random moves38 plies · adjudicated: decisive advantage · $0.362Standard as whiteLost vs Stockfish 170077 plies · adjudicated: decisive advantage · $0.845Chess960 as whiteLost vs Stockfish 150059 plies · adjudicated: decisive advantage · $1.02Standard as blackWon vs Stockfish 132054 plies · checkmate · $0.531Chess960 as blackLost vs Stockfish 132039 plies · checkmate · $0.553Standard as whiteWon vs Skill 0, 10% random moves47 plies · checkmate · $0.644Chess960 as whiteWon vs Skill 0, 10% random moves49 plies · adjudicated: decisive advantage · $0.571Standard as blackLost vs Stockfish 1500158 plies · adjudicated: decisive advantage · $2.17Chess960 as blackLost vs Stockfish Skill 034 plies · adjudicated: decisive advantage · $0.589Chess960 as whiteWon vs Skill 0, 25% random moves99 plies · checkmate · $1.59Standard as whiteWon vs Skill 0, 25% random moves21 plies · adjudicated: decisive advantage · $0.136