Claude Fable 5.1 vs GPT-6 Astra
Claude Fable 5.1 costs $10.00 / $50.00 and GPT-6 Astra costs $10.00 / $50.00 per million input / output tokens. At a typical 3:1 mix, Claude Fable 5.1 is about the same price.
Claude Fable 5.1
Anthropic
Input
$10.00
per 1M
Output
$50.00
per 1M
Cached
$0.25
1M context
GPT-6 Astra
OpenAI
Input
$10.00
per 1M
Output
$50.00
per 1M
Cached
$1.00
1.05M context
Side by side
Green marks the cheaper price, larger context window, bigger discount or higher score.
| Detail | Claude Fable 5.1 | GPT-6 Astra |
|---|---|---|
| Input per 1M | $10.00 | $10.00 |
| Output per 1M | $50.00 | $50.00 |
| Blended per 1M (3:1) | $20.00 | $20.00 |
| Cached input per 1M | $0.25 | $1.00 |
| Batch or off-peak discount | 50% (batch) | 50% (batch) |
| Long prompts | Same rate at any length | Over 272K: 2× in, 1.5× out |
| Context window | 1M | 1.05M |
| Released | 1 Sep 2026 | 3 Sep 2026 |
| Open weights | No | No |
| Arena text score | 1501 | 1478 |
| Verified | 27 Sep 2026 | 27 Sep 2026 |
Sources: Anthropic pricing and OpenAI pricing.
Monthly cost on three workloads
List prices, no batch discount. The cached share applies where a model has a cache rate.
| Workload | Claude Fable 5.1 | GPT-6 Astra | Difference |
|---|---|---|---|
| Customer chat assistant50,000 conversations a month, about 2,000 tokens in and 400 out each; 50% cached | $1,513 | $1,550 | $37.50 |
| Document Q&A (RAG)20,000 questions a month over retrieved documents, 12,000 in and 600 out; 30% cached | $2,298 | $2,352 | $54.00 |
| Coding agent400 tasks a month, 40 steps each with a growing context; 85% cached | $1,684 | $2,163 | $478 |
How they differ
- GPT-6 Astra accepts longer prompts (1.05M vs 1M tokens).
- Cached input is cheaper on Claude Fable 5.1 ($0.25 vs $1), which favours agents and chat apps that resend the same context.
- On the Arena text leaderboard (25 Sep 2026), Claude Fable 5.1 scores higher (1501 vs 1478). Test both on your own prompts before deciding.
Recent changes
All changes- OpenAI launched GPT-6 Sol at $2 / $10 and GPT-6 Luna at $0.10 / $0.50.
- OpenAI launched GPT-6 Astra at $10 / $50, its most expensive standard model.
- Claude Fable 5.1 replaced Fable 5 at the same $10 / $50, with cache reads cut to $0.25.
- Claude Fable 5 returned to the API after the US Commerce Department lifted export controls on 30 June.
- Anthropic suspended Claude Fable 5 and Mythos 5 for all customers after a US export-control directive.
