Claude Opus 5 vs Claude Sonnet 5.5: Specs & Benchmark Comparison
Claude Opus 5 and Claude Sonnet 5.5 both come from Anthropic, Claude Opus 5 was released in July 2026, and Claude Sonnet 5.5 followed 2 months later in September 2026.
The two models share 7 published benchmarks. Claude Sonnet 5.5 leads on 4 of them, Claude Opus 5 on 2. The widest gaps are on Terminal-Bench 4.0, where Claude Sonnet 5.5 scores 70.6% against 51.8%; AutomationBench, where Claude Sonnet 5.5 scores 44.7% against 26.0%. Averaged across everything we track, Claude Opus 5 sits at 55.0% and Claude Sonnet 5.5 at 67.4%.
Claude Sonnet 5.5 is the cheaper API at $2 per million input tokens and $10 per million output tokens, roughly 3 times cheaper than Claude Opus 5 at $5 and $25. Both accept a context window of about 1M tokens. Both accept text and images as input.
| Characteristic | Claude Opus 5 | Claude Sonnet 5.5 |
|---|---|---|
| Company | Anthropic | Anthropic |
| Release Date | July 24, 2026 | September 28, 2026 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 1.0M |
| Context (output) | 128K | 128K |
| Input Price / 1M | $5.00 | $2.00 |
| Output Price / 1M | $25.00 | $10.00 |
| Average Score | 55.0% | 67.4% |
| Benchmarks | ||
| Terminal-Bench 4.0 | 51.8% | 70.6% |
| AutomationBench | 26.0% | 44.7% |
| HealthBench Professional | 59.8% | 69.2% |
| DeepSWE 1.1 | 68.8% | 71.0% |
| FrontierCode 1.1 | 53.4% | 52.1% |
| BioMysteryBench | 90.1% | 89.2% |
| Legal Agent Benchmark | 11.7% | 11.7% |
Visual Benchmark Comparison
Verdict
Claude Sonnet 5.5 leads in 2 out of 4 comparison categories.
Both models show comparable average scores: Claude Opus 5 — 0.5, Claude Sonnet 5.5 — 0.7.
Claude Sonnet 5.5 is 2.5x cheaper: input $2.00/1M vs $5.00/1M tokens.
Same context size: 1M tokens.
Claude Sonnet 5.5 is newer: released 9/28/2026 vs 7/24/2026.
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Frequently Asked Questions
Which is better for coding — Claude Opus 5 or Claude Sonnet 5.5?
Which model is cheaper — Claude Opus 5 or Claude Sonnet 5.5?
Which has a larger context window — Claude Opus 5 or Claude Sonnet 5.5?
The Claude Opus 5 and Claude Sonnet 5.5 comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Opus 5 or Claude Sonnet 5.5 page. See also the complete list of AI model comparisons.