Which has the larger context window, GPT-6.1 Sol and Grok 4.5?

GPT-6.1 Sol has the largest context window: GPT-6.1 Sol 1,050,000 tokens and Grok 4.5 500,000 tokens.

Can I switch between GPT-6.1 Sol 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 (openai/gpt-6.1-sol, x-ai/grok-4.5).

GPT-6.1 Sol vs Grok 4.5

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

GPT-6.1 Sol OpenAIopenai/gpt-6.1-sol

Grok 4.5 xAIx-ai/grok-4.5

Creator

OpenAI

xAI

Released

Sep 29, 2026

Jul 8, 2026

Context window

1.05M

500K

Max output

128K

500K

Input / 1MLowest provider price

$2.00

Output / 1MLowest provider price

$10.00

$6.00

Providers

IntelligenceArtificial Analysis index

51.8

38.8

CodingArtificial Analysis index

—

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

GPT-6.1 Sol vs Grok 4.5: summary

GPT-6.1 Sol 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.

GPT-6.1 Sol, from OpenAI, has a 1,050,000-token context window, costs $2.00/1M input and $10.00/1M output tokens and scores 51.8 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.

GPT-6.1 Sol has the largest context window and GPT-6.1 Sol scores highest for intelligence.

Switch with one line

client = OpenAI(base_url="https://api.fastrouter.ai/api/v1", api_key="<FASTROUTER_API_KEY>") client.chat.completions.create(model="openai/gpt-6.1-sol", messages=[...]) # or client.chat.completions.create(model="x-ai/grok-4.5", messages=[...])

Full API docs

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Benchmark scores sourced from ArtificialAnalysis