Anthropic · Language model

Claude Opus 5.5

Anthropic's new default flagship. Opus 5.5 replaced Opus 5, costs 20% less, and at launch took the top spot on the independent Artificial Analysis Intelligence Index.

MakerAnthropic
ReleasedSeptember 22, 2026
API price (per 1M tokens)$4 in / $20 out
Open weightsNo

Best for

  • Agentic coding
  • Long, multi-step knowledge work
  • Writing and analysis

Strengths

  • Led six of the nine benchmarks Anthropic published at launch
  • 66.4% on Terminal-Bench 4.0 at extra-high effort
  • Much cheaper than the Fable/Mythos tier

Watch out for

  • Trails GPT-6 Astra on AutomationBench and Terminal-Bench-Science
  • Higher effort settings cost more tokens

Ranking history

EditionPower RankingsCodingBest ValueOpen-Weight WatchImage GenerationVideo Generation
Week 39, 2026#1 (97)#1 (98)————

Head-to-head