Claude Opus 5 or Claude Opus 5.5: which to choose?
Claude Opus 5 (Anthropic) and Claude Opus 5.5 (Anthropic) compared point by point: measured performance, pricing, context and capabilities.
Data as of October 22, 2026
Side-by-side comparison
| Criterion | Claude Opus 5 | Claude Opus 5.5 |
|---|---|---|
| Developer | Anthropic | Anthropic |
| Released | July 24, 2026 | September 22, 2026 |
| Capability index | 92.7 / 100 | 95.9 / 100 |
| Input price | $5 | $4 |
| Output price | $25 | $20 |
| Cost of a typical task | $0.15 | $0.12 |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Maximum output | 128,000 tokens | 128,000 tokens |
| Reasoning mode | Yes | Yes |
| Tool calling | Yes | Yes |
| Accepted inputs | text, image, PDF | text, image, PDF |
| Open weights | No | No |
| Knowledge cutoff | May 2026 | June 2026 |
Two models head to head
Claude Opus 5 and Claude Opus 5.5 are two frontier models, the ones you pick when quality comes first, both built by Anthropic. Claude Opus 5 was released on July 24, 2026, Claude Opus 5.5 on September 22, 2026.
All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.
What the benchmarks say
On our capability index, Claude Opus 5 scores 92.7 out of 100 and Claude Opus 5.5 95.9. Claude Opus 5.5 leads by 3.2 points.
On the 5 benchmarks reported for both, Claude Opus 5 wins 1 time and Claude Opus 5.5 4:
- GPQA Diamond (PhD-level science questions): Claude Opus 5 93.9%, Claude Opus 5.5 90.6%
- OTIS Mock AIME (competition mathematics problems): Claude Opus 5 98.9%, Claude Opus 5.5 100%
- FrontierMath (very hard research-level mathematics): Claude Opus 5 85.6%, Claude Opus 5.5 91.2%
- FrontierCode (advanced programming tasks): Claude Opus 5 53.4%, Claude Opus 5.5 54.6%
- APEX-Agents (professional tasks carried out by an agent): Claude Opus 5 65.8%, Claude Opus 5.5 73.5%
Which one costs less?
Claude Opus 5 costs $5 per million input tokens and $25 per million output tokens; Claude Opus 5.5 costs $4 and $20.
For a typical agent task (read 20,000 tokens, write 2,000), expect $0.15 with Claude Opus 5 versus $0.12 with Claude Opus 5.5. Claude Opus 5.5 is 1.3 times cheaper, a gap that adds up quickly over 1,000 tasks: $30 difference.
Run the numbers with your own volumes in the agent cost calculator.
Context and capabilities
Both models have the same context window: 1,000,000 tokens, roughly 1,500 pages.
Reasoning mode: Claude Opus 5 yes, Claude Opus 5.5 yes. Tool calling: Claude Opus 5 yes, Claude Opus 5.5 yes. Image input: Claude Opus 5 yes, Claude Opus 5.5 yes.
Neither publishes its weights: both are used through an API.
Knowledge cutoff: May 2026 for Claude Opus 5, June 2026 for Claude Opus 5.5.
In short
Our reading of the data:
- Choose Claude Opus 5.5 for a higher capability index, a lower cost and a more recent release.
This verdict relies on public figures; it does not replace a trial on your own tasks.
Other comparisons
Frequently asked questions
Claude Opus 5 or Claude Opus 5.5: which is better?
On our index (Epoch AI data), Claude Opus 5 scores 92.7 and Claude Opus 5.5 95.9 out of 100. The best choice also depends on price and on your use case.
Which one is cheaper?
Claude Opus 5.5. To read 20,000 tokens and write 2,000, expect $0.15 with Claude Opus 5 and $0.12 with Claude Opus 5.5 (prices as of October 22, 2026).
Which one has the larger context window?
Neither: both accept 1,000,000 tokens.
Can I run Claude Opus 5 or Claude Opus 5.5 on my own servers?
No: both are closed models, available through an API.
Data sources
- Models.dev — Model data: models.dev (open-source project)
- OpenRouter — Market prices cross-checked with OpenRouter
- Epoch AI — AI Benchmarking Hub — Epoch AI, “AI Benchmarking Hub”, epoch.ai, CC BY 4.0
Data as of October 22, 2026
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