Claude Opus 4.5 vs Claude Sonnet 5.5
Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 38.2. Claude Sonnet 5.5 is 2.5x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 38.2, ranking #3 overall.
On price, Claude Sonnet 5.5 is roughly 2.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Sonnet 5.5 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Claude Opus 4.5
- you want predictable pricing at $5.00/M input and $25.00/M output
Choose Claude Sonnet 5.5
- overall performance matters — it scores 58.0 and ranks #3 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- cost matters — it's about 2.5x cheaper per token
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Sep 2026
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
11 reported for Claude Opus 4.5 · 47 for Claude Sonnet 5.5
Claude Opus 4.5 and Claude Sonnet 5.5don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 2.5x more expensive than Claude Sonnet 5.5 ($2.00/1M tokens).
For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 2.5x more expensive than Claude Sonnet 5.5 ($10.00/1M tokens).
In conclusion, Claude Opus 4.5 is more expensive than Claude Sonnet 5.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Sonnet 5.5 accepts 1,000,000 input tokens compared to Claude Opus 4.5's 200,000 tokens. Claude Sonnet 5.5 can generate longer responses up to 128,000 tokens, while Claude Opus 4.5 is limited to 64,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Opus 4.5 and Claude Sonnet 5.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Opus 4.5
Claude Sonnet 5.5
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Opus 4.5 was released on 2025-11-24, while Claude Sonnet 5.5 was released on 2026-09-28.
Claude Sonnet 5.5 is 10 months newer than Claude Opus 4.5.
Nov 24, 2025
10 months ago
Sep 28, 2026
4 days ago
10mo newerKnowledge Cutoff
When training data ends
Claude Opus 4.5 has a knowledge cutoff of 2025-03-31, while Claude Sonnet 5.5 has a cutoff of 2026-06-01.
Claude Sonnet 5.5 has more recent training data (up to 2026-06-01), making it potentially better informed about events through that date compared to Claude Opus 4.5 (2025-03-31).
Mar 2025
Jun 2026
1.3 yr newerProvider Availability
Claude Opus 4.5 is available from Anthropic. Claude Sonnet 5.5 is available from Anthropic.
Claude Opus 4.5
Claude Sonnet 5.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Opus 4.5 and Claude Sonnet 5.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Opus 4.5 vs Claude Sonnet 5.5.