Anthropic's most powerful model and OpenAI's top flagship list identical input, output and cache-write prices. The differences are in the fine print: what a cache hit costs and what happens past 272K tokens.
On a plain chat or document workload, Claude Fable 5.1 and GPT-6 Astra cost the same. Fable 5.1 pulls ahead when you lean on prompt caching ($0.25 vs $1.00 per cached 1M tokens) or send prompts above 272K tokens, where Astra's rate rises and Fable's does not.
| Claude Fable 5.1 | GPT-6 Astra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Tier | Flagship | Flagship |
| Input / 1M tokens | $10.00 | $10.00 |
| Output / 1M tokens | $50.00 | $50.00 |
| Cache hit / 1M | $0.25 | $1.00 |
| Cache write / 1M | $12.50 | $12.50 |
| Context window | 1M | 1M |
| Notes | Most powerful; released Sep 1, 2026, replacing Fable 5 at same per-token price (cache reads cut 75% to $0.25) | New top flagship (Sep 3, 2026); rolling out to Plus/Pro/Business/Enterprise; >272K tokens: $20/$75, cache $2 |
Both charge $10.00 per 1M input tokens and $50.00 per 1M output tokens.
| Workload | Claude Fable 5.1 | GPT-6 Astra | Difference |
|---|---|---|---|
| Support chatbot 10,000 conversations × (2,000 input + 400 output tokens) | $400 | $400 | — |
| Document Q&A 1,000 questions × (30,000 input + 800 output tokens) | $340 | $340 | — |
| Coding agent session 4M input tokens (90% cache hits) + 150,000 output tokens | $12.40 | $15.10 | Claude Fable 5.1 saves $2.70 |
Standard rates per 1M tokens from data on this site. The coding-agent row assumes 90% of input is read from the prompt cache (full input price where a model has no cache rate). Cache-write fees, batch discounts and long-context surcharges listed in the notes are not included. Updated November 2, 2026.
your workload re-reads a large cached context — coding agents, long-running assistants — or regularly exceeds 272K tokens per request, since Fable keeps standard pricing across its full window.
you are already on OpenAI's platform, your prompts are short, and you value OpenAI's 12-hour cache option or its half-price Flex tier for latency-tolerant traffic.
Anthropic prices Fable 5.1 cache hits at 2.5% of input ($0.25), down from Fable 5's rate. Astra's cache hit is 10% of input ($1.00). The cache-write price is identical ($12.50), but lifetimes differ: Anthropic's standard write lasts 5 minutes (a 1-hour write costs 2× input), OpenAI's lasts 30 minutes, with a 12-hour option. Agents that pause for longer than 5 minutes between turns may pay more cache writes on Anthropic than the rate alone suggests.
Above 272K tokens Astra charges 2× input and 1.5× output. Anthropic includes Fable 5.1's full 1M window at standard rates. For whole-codebase or long-document calls, Fable 5.1 is the cheaper of the two at the same nominal price.
At this price point, check whether you need the top model at all. Anthropic's Claude Opus 5.5 lists $4.00/$20.00, and Anthropic positions it close to Fable 5.1 on most tasks. On OpenAI's side, GPT-6.1 Sol is $2.00/$10.00. Both providers' Batch APIs halve the rate for jobs that can wait.
Their input ($10.00), output ($50.00) and cache-write ($12.50) rates are identical. Cache hits differ: $0.25 on Fable 5.1 vs $1.00 on Astra.
Claude Fable 5.1. GPT-6 Astra moves to a higher rate above 272K tokens; Anthropic bills Fable 5.1's full window at standard pricing.
Claude Opus 5.5 costs $4.00/$20.00 per 1M tokens, and Anthropic positions it close to Fable 5.1 on most tasks. Test both on your own tasks.
How we choose: prices come from each vendor's official pricing page and are re-checked every week. We take no affiliate fees, so rankings aren't for sale.