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Nemotron 3 Ultra 550B A55B vs GPT-6 Luna

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

Estimate monthly cost for these models
Metric
Nemotron 3 Ultra 550B A55BNVIDIAnvidia/nemotron-3-ultra-550b-a55b
GPT-6 LunaOpenAIopenai/gpt-6-luna
Creator
NVIDIA
OpenAI
Released
May 16, 2026
Sep 22, 2026
Context window
262K
400K (best)
Max output
16K
128K (best)
Input / 1MLowest provider price
$0.50
$0.10 (best)
Output / 1MLowest provider price
$2.20
$0.50 (best)
Providers
1
1
IntelligenceArtificial Analysis index
11.8
27.9 (best)
Accepts
Text
Files, Image, Text
Produces
Text
Text
Tool calling
Yes
Yes
Structured output
Yes
Yes
Reasoning
Yes
Yes

Nemotron 3 Ultra 550B A55B vs GPT-6 Luna: summary

Nemotron 3 Ultra 550B A55B 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.

Nemotron 3 Ultra 550B A55B, from NVIDIA, has a 262,144-token context window, costs $0.50/1M input and $2.20/1M output tokens and scores 11.8 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 27.9 on the Artificial Analysis Intelligence Index.

GPT-6 Luna is the cheapest on input, 5× cheaper than the next model, GPT-6 Luna has the largest context window and GPT-6 Luna 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="nvidia/nemotron-3-ultra-550b-a55b", messages=[...]) # or client.chat.completions.create(model="openai/gpt-6-luna", messages=[...])
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Benchmark scores sourced from ArtificialAnalysis