Side by side
| GPT-6 Astra | Claude Fable 5.1 | |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Input / 1M tokens | $10.00 | $10.00 |
| Output / 1M tokens | $50.00 | $50.00 |
| Output price ÷ input price | 5.0x | 5.0x |
| Blended / 1M (3:1) | $20.00 | $20.00 |
| Context window | 1.05M | 1M |
| ≈ English words that fit | 788,000 | 750,000 |
| 1,000 calls (2000+500 tok) | $45.00 | $45.00 |
| AA Intelligence Index | 57 | 50 |
| LMArena Text | 1476 | 1504 |
| Blended $ per AA index point | $0.351 | $0.400 |
List prices from official pages (OpenAI, Anthropic), verified 2026-11-04. Benchmarks from public leaderboards (Artificial Analysis, LMArena), not run by us. Word counts use the rough 0.75 words per token rule for English. "$ per index point" is our own arithmetic (blended price ÷ index score), a rough value-for-money signal, not a benchmark.
What real workloads cost
Four example request shapes, priced at list rates with no caching or batch discounts. Monthly figures assume 100,000 requests.
| Workload | GPT-6 Astra | Claude Fable 5.1 | Gap |
|---|---|---|---|
| Support chat reply a short system prompt, recent chat history and a reply | $0.0450 each $4,500.00 / mo | $0.0450 each $4,500.00 / mo | same cost |
| RAG answer a question plus about 20K tokens of retrieved documents, and a cited answer | $0.2400 each $24,000.00 / mo | $0.2400 each $24,000.00 / mo | same cost |
| 10-step agent task an agent loop of 10 model calls, each re-reading about 8K tokens of context and emitting a 400-token tool call | $1.00 each $100,000.00 / mo | $1.00 each $100,000.00 / mo | same cost |
| Long-report summary one 200K-token document summarized into about 2K tokens | $2.10 each $210,000.00 / mo | $2.10 each $210,000.00 / mo | same cost |
When to pick each
- Pick GPT-6 Astra when cost is the main constraint: at list prices it is the same price as Claude Fable 5.1 on a typical 2,000-in / 500-out call.
- Pick GPT-6 Astra when answer quality matters more than price: it scores 57 vs 50 on the Artificial Analysis Intelligence Index.
- Pick GPT-6 Astra if a single prompt can exceed 1M tokens (about 750,000 English words): its window is 1.05M.
- They come from different providers (OpenAI and Anthropic), so switching means a second API key, SDK and billing account, and tool-calling formats differ. Our schema converter outputs both formats from one JSON Schema.
Context and pricing limits
- GPT-6 Astra: 1.05M tokens of context. Claude Fable 5.1: 1M. GPT-6 Astra holds 1.1x more.
- GPT-6 Astra: Short-context (<=272K input) price. The prices above are this tier; check the official pricing page before committing.
- Cached input, batch and off-peak discounts can cut real bills a lot and differ by provider; they are not included here.
FAQ
Is GPT-6 Astra cheaper than Claude Fable 5.1?
On our 2000-in / 500-out example they cost the same.
Which has the larger context window?
GPT-6 Astra, with 1.05M tokens vs 1M.
Which scores higher on benchmarks?
GPT-6 Astra scores 57 vs 50 on the Artificial Analysis Intelligence Index. On LMArena Text, GPT-6 Astra has 1476 and Claude Fable 5.1 1504. Benchmarks are averages; test both on your own prompts.
Run your own numbers in the token cost estimator · GPT-6 Astra pricing · Claude Fable 5.1 pricing · All comparisons