Which is cheaper, Claude Sonnet 5.5 and Gemini 3.7 Flash?

Gemini 3.7 Flash has the lowest input price. Per 1M input tokens: Claude Sonnet 5.5 from $2.00 and Gemini 3.7 Flash from $0.75.

Which has the larger context window, Claude Sonnet 5.5 and Gemini 3.7 Flash?

Gemini 3.7 Flash has the largest context window: Claude Sonnet 5.5 1,000,000 tokens and Gemini 3.7 Flash 1,048,576 tokens.

Which is smarter, Claude Sonnet 5.5 and Gemini 3.7 Flash?

Claude Sonnet 5.5 scores highest on the Artificial Analysis Intelligence Index: Claude Sonnet 5.5 56.0 and Gemini 3.7 Flash 39.1.

Can I switch between Claude Sonnet 5.5 and Gemini 3.7 Flash 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-sonnet-5.5, google/gemini-3.7-flash).

Claude Sonnet 5.5 vs Gemini 3.7 Flash

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

Claude Sonnet 5.5 Anthropicanthropic/claude-sonnet-5.5

Gemini 3.7 Flash Googlegoogle/gemini-3.7-flash

Creator

Anthropic

Google

Released

Sep 28, 2026

Aug 13, 2026

Context window

1.05M

Max output

128K

66K

Input / 1MLowest provider price

$2.00

$0.75

Output / 1MLowest provider price

$10.00

$3.75

Providers

IntelligenceArtificial Analysis index

56.0

39.1

CodingArtificial Analysis index

—

76.1

Accepts

Text, Image

Text, Image, Audio, Video, Files

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Claude Sonnet 5.5 vs Gemini 3.7 Flash: summary

Claude Sonnet 5.5 and Gemini 3.7 Flash are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Claude Sonnet 5.5, from Anthropic, has a 1,000,000-token context window, costs $2.00/1M input and $10.00/1M output tokens and scores 56.0 on the Artificial Analysis Intelligence Index.

Gemini 3.7 Flash, from Google, has a 1,048,576-token context window, costs from $0.75/1M input and $3.75/1M output tokens across 2 providers and scores 39.1 on the Artificial Analysis Intelligence Index.

Gemini 3.7 Flash is the cheapest on input, 2.7× cheaper than the next model, Gemini 3.7 Flash has the largest context window and Claude Sonnet 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-sonnet-5.5", messages=[...]) # or client.chat.completions.create(model="google/gemini-3.7-flash", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis