Claude Fable 5.1 vs GPT-6 Astra: pricing compared
For a 30-step coding agent run, Claude Fable 5.1 is 1.4x cheaper ($3.63 vs $5.16). Prices verified 2026-10-18.
| Claude Fable 5.1 | GPT-6 Astra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input / 1M | $10.00 | $10.00 |
| Cached input / 1M | $0.25 | $1.00 |
| Output / 1M | $50.00 | $50.00 |
| Batch discount | 50% | 50% |
| Context window | 1M | 1.05M |
| Long-context tier | none | above 272K |
Cost on real workloads
| Workload | Claude Fable 5.1 | GPT-6 Astra |
|---|---|---|
| 10,000 chatbot replies 2,000 input + 400 output tokens each, 50% of the prompt cached | $303 | $310 |
| One 30-step coding agent run 12K system + tools prompt, 1K output and 3K tool result per step, caching on | $3.63 | $5.16 |
| 1M documents classified (batch) 600 input + 20 output tokens each, batch API where available | $3,500 | $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 Fable 5.1 cheaper than GPT-6 Astra?
For a typical 30-step coding agent run with caching, Claude Fable 5.1 costs $3.63 and GPT-6 Astra costs $5.16, so Claude Fable 5.1 is 1.4x cheaper. Per 1M tokens, Claude Fable 5.1 is $10.00 / $50.00 and GPT-6 Astra is $10.00 / $50.00.
Which has the bigger context window?
Claude Fable 5.1: 1,000,000 tokens. GPT-6 Astra: 1,050,000 tokens.