Which is cheaper, Claude Fable 5.1 and Grok 4.5?

Grok 4.5 has the lowest input price. Per 1M input tokens: Claude Fable 5.1 from $10.00 and Grok 4.5 from $2.00.

Which has the larger context window, Claude Fable 5.1 and Grok 4.5?

Claude Fable 5.1 has the largest context window: Claude Fable 5.1 1,000,000 tokens and Grok 4.5 500,000 tokens.

Which is better for coding, Claude Fable 5.1 and Grok 4.5?

Claude Fable 5.1 scores highest on the Artificial Analysis Coding Index: Claude Fable 5.1 79.1 and Grok 4.5 72.4.

Which is smarter, Claude Fable 5.1 and Grok 4.5?

Claude Fable 5.1 scores highest on the Artificial Analysis Intelligence Index: Claude Fable 5.1 51.2 and Grok 4.5 38.8.

Can I switch between Claude Fable 5.1 and Grok 4.5 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, x-ai/grok-4.5).

Claude Fable 5.1 vs Grok 4.5

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

Grok 4.5 xAIx-ai/grok-4.5

Creator

Anthropic

xAI

Released

Sep 1, 2026

Jul 8, 2026

Context window

500K

Max output

128K

500K

Input / 1MLowest provider price

$10.00

$2.00

Output / 1MLowest provider price

$50.00

$6.00

Providers

IntelligenceArtificial Analysis index

51.2

38.8

CodingArtificial Analysis index

79.1

72.4

LatencyMedian time to first token

—

81s

ThroughputMedian tokens per second

—

<1 t/s

Accepts

Text, Image, Files

Text, Image

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Claude Fable 5.1 vs Grok 4.5: summary

Claude Fable 5.1 and Grok 4.5 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.

Grok 4.5, from xAI, has a 500,000-token context window, costs $2.00/1M input and $6.00/1M output tokens and scores 38.8 on the Artificial Analysis Intelligence Index.

Grok 4.5 is the cheapest on input, 5× cheaper than the next model, Claude Fable 5.1 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="x-ai/grok-4.5", messages=[...])

Full API docs

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More comparisons

Benchmark scores sourced from ArtificialAnalysis