Which has the larger context window, Claude Fable 5.1 and GPT-6 Astra?

GPT-6 Astra has the largest context window: Claude Fable 5.1 1,000,000 tokens and GPT-6 Astra 1,050,000 tokens.

Which is better for coding, Claude Fable 5.1 and GPT-6 Astra?

Claude Fable 5.1 scores highest on the Artificial Analysis Coding Index: Claude Fable 5.1 79.1 and GPT-6 Astra 77.1.

Which is smarter, Claude Fable 5.1 and GPT-6 Astra?

Claude Fable 5.1 scores highest on the Artificial Analysis Intelligence Index: Claude Fable 5.1 51.2 and GPT-6 Astra 50.9.

Can I switch between Claude Fable 5.1 and GPT-6 Astra without changing my code?

Yes. All of them are served through FastRouter's OpenAI-compatible API, so switching is a change of the model parameter (anthropic/claude-fable-5.1, openai/gpt-6-astra).

Claude Fable 5.1 vs GPT-6 Astra

Side-by-side pricing per provider, context window, benchmark scores and speed, all on one OpenAI-compatible API.

Claude Fable 5.1 Anthropicanthropic/claude-fable-5.1

GPT-6 Astra OpenAIopenai/gpt-6-astra

Creator

Anthropic

OpenAI

Released

Sep 1, 2026

Sep 4, 2026

Context window

1.05M

Max output

128K

Input / 1MLowest provider price

$10.00

Output / 1MLowest provider price

$50.00

Providers

IntelligenceArtificial Analysis index

51.2

50.9

CodingArtificial Analysis index

79.1

77.1

Accepts

Text, Image, Files

Text, Image

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Claude Fable 5.1 vs GPT-6 Astra: summary

Claude Fable 5.1 and GPT-6 Astra are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Claude Fable 5.1, from Anthropic, has a 1,000,000-token context window, costs $10.00/1M input and $50.00/1M output tokens and scores 51.2 on the Artificial Analysis Intelligence Index.

GPT-6 Astra, from OpenAI, has a 1,050,000-token context window, costs $10.00/1M input and $50.00/1M output tokens and scores 50.9 on the Artificial Analysis Intelligence Index.

GPT-6 Astra has the largest context window, Claude Fable 5.1 scores highest for intelligence and Claude Fable 5.1 leads on coding.

Switch with one line

client = OpenAI(base_url="https://api.fastrouter.ai/api/v1", api_key="<FASTROUTER_API_KEY>") client.chat.completions.create(model="anthropic/claude-fable-5.1", messages=[...]) # or client.chat.completions.create(model="openai/gpt-6-astra", messages=[...])

Full API docs

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More comparisons

Benchmark scores sourced from ArtificialAnalysis