Claude Opus 5.5 vs GPT-6 Astra: pricing compared
For a 30-step coding agent run, Claude Opus 5.5 is 3.1x cheaper ($1.66 vs $5.16). Prices verified 2026-10-18.
| Claude Opus 5.5 | GPT-6 Astra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M | $4.00 | $10.00 |
| Cached input / 1M | $0.20 | $1.00 |
| Output / 1M | $20.00 | $50.00 |
| Batch discount | 50% | 50% |
| Context window | 1M | 1.05M |
| Long-context tier | none | above 272K |
Cost on real workloads
| Workload | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| 10,000 chatbot replies 2,000 input + 400 output tokens each, 50% of the prompt cached | $122 | $310 |
| One 30-step coding agent run 12K system + tools prompt, 1K output and 3K tool result per step, caching on | $1.66 | $5.16 |
| 1M documents classified (batch) 600 input + 20 output tokens each, batch API where available | $1,400 | $3,500 |
Price is only half the decision: a cheaper model that needs more steps or retries can cost more per finished task. Run your own numbers in the calculator (both models pinned), or see how both rank in the use-case guides.
FAQ
Is Claude Opus 5.5 cheaper than GPT-6 Astra?
For a typical 30-step coding agent run with caching, Claude Opus 5.5 costs $1.66 and GPT-6 Astra costs $5.16, so Claude Opus 5.5 is 3.1x cheaper. Per 1M tokens, Claude Opus 5.5 is $4.00 / $20.00 and GPT-6 Astra is $10.00 / $50.00.
Which has the bigger context window?
Claude Opus 5.5: 1,000,000 tokens. GPT-6 Astra: 1,050,000 tokens.