LogoFastRouter

GPT-6 Luna vs Grok 4.6

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

Metric
GPT-6 LunaOpenAIopenai/gpt-6-luna
Grok 4.6xAIx-ai/grok-4.6
Creator
OpenAI
xAI
Released
Sep 22, 2026
Aug 12, 2026
Context window
400K
500K (best)
Max output
128K
500K (best)
Input / 1MLowest provider price
$0.10 (best)
$2.00
Output / 1MLowest provider price
$0.50 (best)
$6.00
Providers
1
1
IntelligenceArtificial Analysis index
38.1
44.3 (best)
CodingArtificial Analysis index
—
76.8
Accepts
Files, Image, Text
Text, Image
Produces
Text
Text
Tool calling
Yes
Yes
Structured output
Yes
Yes
Reasoning
Yes
No

GPT-6 Luna vs Grok 4.6: summary

GPT-6 Luna and Grok 4.6 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 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.

Grok 4.6, from xAI, has a 500,000-token context window, costs $2.00/1M input and $6.00/1M output tokens and scores 44.3 on the Artificial Analysis Intelligence Index.

GPT-6 Luna is the cheapest on input, 20× cheaper than the next model, Grok 4.6 has the largest context window and Grok 4.6 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-luna", messages=[...]) # or client.chat.completions.create(model="x-ai/grok-4.6", messages=[...])
Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis