# Claude Sonnet 4.5 vs Claude Sonnet 5.5

As of Oct 15, 2026, Claude Sonnet 4.5 leads Claude Sonnet 5.5 in 0 of 7 shared categories.

Claude Sonnet 4.5: $6 per 1M blended tokens.

Claude Sonnet 5.5: $4.000000000000001 per 1M blended tokens.

Claude Sonnet 4.5: closed weights.

Claude Sonnet 5.5: closed weights.

- Which to pick, General LLM: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in General LLM at #29 against #62.
- Which to pick, Reasoning: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Reasoning at #18 against #51.
- Which to pick, Math: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Math at #4 against #25.
- Which to pick, Science: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Science at #3 against #82.
- Which to pick, Coding › Web dev: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Coding › Web dev at #3 against #86.
- Which to pick, Long context: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Long context at #11 against #34.
- Which to pick, Factuality: As of Oct 15, 2026, Claude Sonnet 5.5 leads Claude Sonnet 4.5 in Factuality at #17 against #61.

As of Oct 15, 2026, Claude Sonnet 4.5 is a former state-of-the-art holder in General LLM (since Oct 3, 2025; sources LMArena Text (style-controlled, overall); methodology v1.0).

As of Oct 15, 2026, Claude Sonnet 5.5 is tied for state of the art in Coding (since Oct 6, 2026; sources Terminal-Bench 4.0; methodology v1.0).