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GPT-6 Astra vs Claude Fable 5.1
A straight cost comparison of GPT-6 Astra (OpenAI) and Claude Fable 5.1 (Anthropic), per 1,000,000 tokens, verified October 2026.
Rate-by-rate comparison
| Metric | GPT-6 Astra | Claude Fable 5.1 | Winner |
|---|---|---|---|
| Input / 1M | $10 | $10 | Tie |
| Cached input / 1M | $1 | $0.25 | Claude Fable 5.1 |
| Cache write / 1M | $12.50 | $12.50 | Tie |
| Output / 1M | $50 | $50 | Tie |
| Context window | 1,050,000 | 1,000,000 | GPT-6 Astra |
| Batch API | Yes | Yes | Tie |
| Long-context tier | > 272,000 | None | — |
For per-token metrics, the lower number wins. For context window and batch support, the higher or broader option wins. A dash means the provider does not publish that rate: a missing cache-write fee means writes are not billed per token, while a missing cached-input rate means cache hits bill at the full input rate.
Blended cost: 1M input + 250K output
| Model | Blended cost | Difference |
|---|---|---|
| GPT-6 Astra | $22.50 | Tie |
| Claude Fable 5.1 | $22.50 | Tie |
Three workloads, two bills
| Workload | GPT-6 Astra | Claude Fable 5.1 | Winner |
|---|---|---|---|
| Support chat 1,000 requests · 4K input / 600 output | $70 | $70 | Tie |
| RAG with caching 1,000 requests · 50K input (45K cached) / 1K output | $146 | $112 | Claude Fable 5.1 |
| Nightly batch job 10,000 requests · 10K input / 2K output | $1000 | $1000 | Tie |
Which one should you pick?
GPT-6 Astra wins on none of the three workloads above, while Claude Fable 5.1 wins on cached RAG.
Beyond price, the two differ on cached-input rate ($1 vs $0.25); context window (1,050,000 vs 1,000,000); long-context tier (yes, above 272,000 vs none).
Batch mode is available on GPT-6 Astra and Claude Fable 5.1, which halves the nightly job. Both publish cached-input discounts, so a stable system prompt is worth caching on either.
FAQ
Is GPT-6 Astra cheaper than Claude Fable 5.1?
No — they are priced identically at $22.50 on a blended 1M-input-plus-250K-output workload, with the same per-token rates. Choose on context window, throughput or output quality instead.
Which handles longer prompts, GPT-6 Astra or Claude Fable 5.1?
GPT-6 Astra has the larger context window (1,050,000 vs 1,000,000 tokens). Watch the long-context threshold on GPT-6 Astra: rates rise once input passes it.
Do both models support prompt caching?
GPT-6 Astra bills cached reads at $1 per 1M; Claude Fable 5.1 at $0.25.