Which is cheaper, Gemini 3.7 Flash and GPT-6 Luna?

GPT-6 Luna has the lowest input price. Per 1M input tokens: Gemini 3.7 Flash from $0.75 and GPT-6 Luna from $0.10.

Which has the larger context window, Gemini 3.7 Flash and GPT-6 Luna?

Gemini 3.7 Flash has the largest context window: Gemini 3.7 Flash 1,048,576 tokens and GPT-6 Luna 400,000 tokens.

Which is smarter, Gemini 3.7 Flash and GPT-6 Luna?

Gemini 3.7 Flash scores highest on the Artificial Analysis Intelligence Index: Gemini 3.7 Flash 39.1 and GPT-6 Luna 38.1.

Can I switch between Gemini 3.7 Flash and GPT-6 Luna 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 (google/gemini-3.7-flash, openai/gpt-6-luna).

Gemini 3.7 Flash vs GPT-6 Luna

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

Gemini 3.7 Flash Googlegoogle/gemini-3.7-flash

GPT-6 Luna OpenAIopenai/gpt-6-luna

Creator

Google

OpenAI

Released

Aug 13, 2026

Sep 22, 2026

Context window

1.05M

400K

Max output

66K

128K

Input / 1MLowest provider price

$0.75

$0.10

Output / 1MLowest provider price

$3.75

$0.50

Providers

IntelligenceArtificial Analysis index

39.1

38.1

CodingArtificial Analysis index

76.1

—

Accepts

Text, Image, Audio, Video, Files

Files, Image, Text

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Gemini 3.7 Flash vs GPT-6 Luna: summary

Gemini 3.7 Flash and GPT-6 Luna are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

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.

GPT-6 Luna, from OpenAI, has a 400,000-token context window, costs $0.10/1M input and $0.50/1M output tokens and scores 38.1 on the Artificial Analysis Intelligence Index.

GPT-6 Luna is the cheapest on input, 7.5× cheaper than the next model, Gemini 3.7 Flash has the largest context window and Gemini 3.7 Flash 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="google/gemini-3.7-flash", messages=[...]) # or client.chat.completions.create(model="openai/gpt-6-luna", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis