Claude 3.5 Sonnet vs Claude Opus 5.5
Claude Opus 5.5 leads the LLM Stats Score 59.7 to 15.9. Claude 3.5 Sonnet is 1.3x cheaper per token.
Anthropic · Anthropic · Updated for 2026
Which is better?
Claude Opus 5.5 leads the overall LLM Stats Score 59.7 to 15.9, ranking #1 overall.
On price, Claude 3.5 Sonnet is roughly 1.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Opus 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 3.5 Sonnet
- cost matters — it's about 1.3x cheaper per token
Choose Claude Opus 5.5
- overall performance matters — it scores 59.7 and ranks #1 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- 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
9 reported for Claude 3.5 Sonnet · 31 for Claude Opus 5.5
Claude 3.5 Sonnet and Claude Opus 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 3.5 Sonnet ($3.00/1M tokens) is 1.3x cheaper than Claude Opus 5.5 ($4.00/1M tokens).
For output processing, Claude 3.5 Sonnet ($15.00/1M tokens) is 1.3x cheaper than Claude Opus 5.5 ($20.00/1M tokens).
In conclusion, Claude Opus 5.5 is more expensive than Claude 3.5 Sonnet.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Opus 5.5 accepts 1,000,000 input tokens compared to Claude 3.5 Sonnet's 200,000 tokens. Claude 3.5 Sonnet can generate longer responses up to 200,000 tokens, while Claude Opus 5.5 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude 3.5 Sonnet and Claude Opus 5.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude 3.5 Sonnet
Claude Opus 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 3.5 Sonnet was released on 2024-06-21, while Claude Opus 5.5 was released on 2026-09-22.
Claude Opus 5.5 is 27 months newer than Claude 3.5 Sonnet.
Jun 21, 2024
2.3 years ago
Sep 22, 2026
0 days ago
2.3yr newerKnowledge Cutoff
When training data ends
Claude Opus 5.5 has a documented knowledge cutoff of 2026-06-01, while Claude 3.5 Sonnet's cutoff date is not specified.
We can confirm Claude Opus 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Claude 3.5 Sonnet's cutoff date.
—
Jun 2026
Provider Availability
Claude 3.5 Sonnet is available from Bedrock, Google. Claude Opus 5.5 is available from Anthropic.
Claude 3.5 Sonnet
Claude Opus 5.5
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude 3.5 Sonnet and Claude Opus 5.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude 3.5 Sonnet vs Claude Opus 5.5.