GPT-6 Astra vs Claude Fable 5.1
There is no clear pick: the AIGROW small-business benchmark cannot tell the two apart, and their list prices are the same. GPT-6 Astra passed 17 of 20 tasks and costs $10 in and $50 out per million tokens; Claude Fable 5.1 passed 17 and costs $10 in and $50 out.
Run both up to 75% below list price. $25 a month brings $110 of API credit and cancels any time; $25 once buys $100. US dollars, standard rate, shortest context band. Cost per pass from the AIGROW small-business benchmark. Newer comparison: Claude Fable 5.2 vs GPT-6 Astra
- GPT-6 Astra
- $27.91
- Tasks passed
- 17 of 20
- Claude Fable 5.1
- $33.11
- Tasks passed
- 17 of 20
AIGROW small-business benchmark, failed runs included.
GPT-6 Astra against the previous Claude Fable, at the same $10 / $50 list price. GPT-6 Astra costs $27.91 per 1,000 passing answers on the AIGROW small-business benchmark, Claude Fable 5.1 $33.11. 1,000 support replies cost $50.00 on either. GPT-6 Astra was released on 3 Sep 2026, Claude Fable 5.1 was released on 1 Sep 2026.
What each one costs
The API price per million tokens and the cheapest app plan with each model, from the makers’ own pages. Each name opens that model’s full price page.
- GPT-6 Astra
- On the OpenAI API, GPT-6 Astra costs $10 per million input tokens and $50 per million output tokens. In ChatGPT, the cheapest plan with it is Plus at $20/mo. Plan prices read 22 October 2026. AIGROW API credit runs GPT-6 Astra at $2.50 / $12.50 per million input / output tokens, 75% below list price. See API credit
- Claude Fable 5.1
- On the Anthropic API, Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens. In Claude, the cheapest plan with it is Max 5x at $100/mo. Plan prices read 22 October 2026. AIGROW API credit runs Claude Fable 5.1 at $4.00 / $20.00 per million input / output tokens, up to 60% below list price. See API credit
$25 a month brings $110 of API credit and cancels any time; $25 once buys $100.
Side by side
Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.
| Fact | GPT-6 Astra | Claude Fable 5.1 |
|---|---|---|
| Maker | OpenAI | Anthropic |
| Tier | Flagships | Flagships |
| Input, per M tokens | $10.00 | $10.00 |
| Output, per M tokens | $50.00 | $50.00 |
| Cached input | $1.00 | $0.25 |
| Context window | 1.05M | 1M |
| Released | 3 Sep 2026 | 1 Sep 2026 |
| Weights | Closed weights | Closed weights |
What a job costs on each
1,000 runs of each job at the two list prices. The gap moves from job to job because the models price input, output and cached context differently.
| Job | GPT-6 Astra | Claude Fable 5.1 | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $50.00 | $50.00 | Even |
| Document summary25,000 in, 1,000 out. | $300 | $300 | Even |
| Agent task80,000 in (70,000 cached), 3,000 out. | $320 | $268 | Claude Fable 5.1, 16% less |
The token counts are ours, chosen to look like real work; the prices are the makers’. A model with no published cache price bills the agent task’s repeated context at its full input rate.
The small print
What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.
- GPT-6 Astra
- Requests above 272K input tokens bill 2x input and 1.5x output ($20 / $75, cached $2). Cache write $12.50. Batch and Flex 50% off, Fast mode 2x, Ultrafast mode $60 / $300 since 29 September 2026. Data residency adds 10%. Context 1,050,000 with max input 922K. OpenAI’s pricing page
- Claude Fable 5.1
- Legacy model, still available; the current Fable is Claude Fable 5.2, and Anthropic lists no retirement before 1 September 2027. Cache read is 0.025x input on this model ($0.25). Cache write $12.50 (5 min) or $20 (1 h). Batch API 50% off. US-only inference bills 1.1x. Full context window billed at standard rates. Anthropic’s pricing page
Other comparisons
Every head to head on the list that involves GPT-6 Astra or Claude Fable 5.1.
Run both up to 75% below list price
AIGROW API credit covers GPT-6 Astra and Claude Fable 5.1 at published rates never above the list prices here, and $25 buys $100 of credit.
Prices checked 12 November 2026