GPT-6 Astra vs Claude Fable 5.1
The top model from each of the two best-known labs, at the same $10 / $50 list price. Both list prices from the makers’ own pages, and what three everyday jobs cost on each.
US dollars, standard rate, shortest context band. Price only: this page does not rank quality.
- GPT-6 Astra
- $50.00
- Claude Fable 5.1
- $50.00
- GPT-6 Astra, per M tokens
- $10 / $50
- Claude Fable 5.1, per M tokens
- $10 / $50
3,000 tokens in and 400 out each, at list price.
Per million tokens, GPT-6 Astra costs $10 in and $50 out; Claude Fable 5.1 costs $10 in and $50 out. 1,000 support replies cost $50.00 on either. GPT-6 Astra reads up to 1.05M tokens at once, Claude Fable 5.1 up to 1M.
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 | Closed |
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. Data residency adds 10%. Context 1,050,000 with max input 922K. OpenAI’s pricing page
- Claude Fable 5.1
- 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 (inference_geo) 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 for a quarter of list price
AIGROW API credit covers GPT-6 Astra and Claude Fable 5.1 and is metered at the list prices above: $25 buys $100 of usage.
Prices checked 22 September 2026