Claude Fable 5.1 vs GPT-6 Astra
Anthropic's Claude Fable 5.1 and OpenAI's GPT-6 Astra, compared on the figures Alevr runs on: list prices, context window, speed and intelligence grades, and the plan that includes each.
Anthropic
Claude Fable 5.1
Anthropic's frontier model: deepest reasoning, long-horizon agents.
- Input / output per M
- $10.00 / $50.00
- Context
- 1M
- In Alevr from
- Pro
OpenAI
GPT-6 Astra
OpenAI's most capable model: built for hard end-to-end reasoning, coding, research, and computer-use work.
- Input / output per M
- $10.00 / $50.00
- Context
- 1.05M
- In Alevr from
- Pro
Side by side.
| Claude Fable 5.1 | GPT-6 Astra | |
|---|---|---|
| Lab | Anthropic | OpenAI |
| Released | Sep 2026 | Sep 2026 |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Input, per M tokens | $10.00 | $10.00 |
| Cached input, per M tokens | $0.25 | $1.00 |
| Output, per M tokens | $50.00 | $50.00 |
| Intelligence grade | 10 / 10Catalog estimate | 10 / 10Catalog estimate |
| Speed grade | 3 / 10Catalog estimate | 4 / 10Catalog estimate |
| Adjustable thinking | Yes | Yes |
| Reads images | Yes | Yes |
| Searches the web in Alevr | Yes | Yes |
| Drives agents and Code | Yes | Yes |
| Included in Alevr from | Pro€24 a month incl. VAT | Pro€24 a month incl. VAT |
Which to pick.
Each answer below is a comparison of the figures above, nothing more. Costs use a chat turn of 800 input and 500 output tokens.
- For the lowest cost per messageNo clear difference
- At list prices, 1,000 requests of a chat turn of 800 input and 500 output tokens cost $33.00 on Claude Fable 5.1 and $33.00 on GPT-6 Astra. That is within 10%, so price does not separate them here.
- For the hardest reasoningNo clear difference
- Both carry the same intelligence grade, 10 out of 10. Neither model has an Artificial Analysis measurement in Alevr's latest benchmark sync yet, so both grades are the catalog's estimates and may move when one lands.
- For quick back-and-forthGPT-6 Astra
- GPT-6 Astra has the higher speed grade, 4 against 3 out of 10.
- For long documentsNo clear difference
- The context windows are close: 1M and 1.05M tokens.
- On a smaller Alevr planNo clear difference
- Both are included from Pro, €24 a month incl. VAT.
Pick Claude Fable 5.1
On these figures it does not come out ahead on any measure here. Its lab's own positioning is in the note above; in Alevr you can try both on the same prompt and judge the answers yourself.
Pick GPT-6 Astra
- for quick back-and-forth
Use both in Alevr.
Alevr puts Claude, GPT, Gemini and 150+ models in one subscription, hosted in France. Both of these are included from Pro, €24 a month incl. VAT. Plans start at €10.80.
More comparisons
- Claude Opus 5.5 vs GPT-6 Astra$4.00 / $20.00 vs $10.00 / $50.00 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol for coding$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol for writing$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs Gemini 3.1 Pro$4.00 / $20.00 vs $2.00 / $12.00 per M tokens
- GPT-6.1 Sol vs Gemini 3.1 Pro$2.00 / $10.00 vs $2.00 / $12.00 per M tokens
Where these figures come from
Prices are each lab's API list price in US dollars per million tokens, as recorded in the model catalog Alevr bills from. Cached input is the rate a prompt-cache hit is billed at. Alevr subscribers do not pay per token: each plan includes a monthly usage budget.
Intelligence and speed are Alevr's 1 to 10 grades. Where Artificial Analysis has measured a model, the grade is computed from its Intelligence Index and median output speed. A model it has not measured yet carries an estimate from the lab's positioning, and the page says so. The benchmark sync last ran on 22 September 2026.
The figures change when labs change their prices. These pages are rebuilt from the same catalog each time Alevr ships, so they match what the app shows.
OpenRouter, a reseller, lists Claude Fable 5.1 (anthropic/claude-fable-5.1) at $10.00 input and $50.00 output per million tokens. Resale rates can differ from the lab's own.
OpenRouter, a reseller, lists GPT-6 Astra (openai/gpt-6-astra) at $10.00 input and $50.00 output per million tokens. Resale rates can differ from the lab's own.