Which has the larger context window, Claude Opus 5.5 and GPT-5.6 Sol?

GPT-5.6 Sol has the largest context window: Claude Opus 5.5 1,000,000 tokens and GPT-5.6 Sol 1,050,000 tokens.

Which is smarter, Claude Opus 5.5 and GPT-5.6 Sol?

Claude Opus 5.5 scores highest on the Artificial Analysis Intelligence Index: Claude Opus 5.5 57.6 and GPT-5.6 Sol 42.3.

Can I switch between Claude Opus 5.5 and GPT-5.6 Sol 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-opus-5.5, openai/gpt-5.6-sol).

Claude Opus 5.5 vs GPT-5.6 Sol

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

Claude Opus 5.5 Anthropicanthropic/claude-opus-5.5

GPT-5.6 Sol OpenAIopenai/gpt-5.6-sol

Creator

Anthropic

OpenAI

Released

Sep 22, 2026

Jul 9, 2026

Context window

1.05M

Max output

128K

Input / 1MLowest provider price

$4.00

Output / 1MLowest provider price

$20.00

Providers

IntelligenceArtificial Analysis index

57.6

42.3

CodingArtificial Analysis index

—

77.2

LatencyMedian time to first token

—

5.7s

ThroughputMedian tokens per second

—

<1 t/s

Accepts

Text, Image, Files

Text, Image

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Claude Opus 5.5 vs GPT-5.6 Sol: summary

Claude Opus 5.5 and GPT-5.6 Sol are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Claude Opus 5.5, from Anthropic, has a 1,000,000-token context window, costs $4.00/1M input and $20.00/1M output tokens and scores 57.6 on the Artificial Analysis Intelligence Index.

GPT-5.6 Sol, from OpenAI, has a 1,050,000-token context window, costs $4.00/1M input and $20.00/1M output tokens and scores 42.3 on the Artificial Analysis Intelligence Index.

GPT-5.6 Sol has the largest context window and Claude Opus 5.5 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="anthropic/claude-opus-5.5", messages=[...]) # or client.chat.completions.create(model="openai/gpt-5.6-sol", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis