Which is cheaper, Kimi K3.1 Pro and Nemotron 3 Ultra 550B A55B?

Nemotron 3 Ultra 550B A55B has the lowest input price. Per 1M input tokens: Kimi K3.1 Pro from $2.00 and Nemotron 3 Ultra 550B A55B from $0.50.

Which has the larger context window, Kimi K3.1 Pro and Nemotron 3 Ultra 550B A55B?

Kimi K3.1 Pro has the largest context window: Kimi K3.1 Pro 1,048,576 tokens and Nemotron 3 Ultra 550B A55B 262,144 tokens.

Which is smarter, Kimi K3.1 Pro and Nemotron 3 Ultra 550B A55B?

Kimi K3.1 Pro scores highest on the Artificial Analysis Intelligence Index: Kimi K3.1 Pro 46.5 and Nemotron 3 Ultra 550B A55B 11.8.

Can I switch between Kimi K3.1 Pro and Nemotron 3 Ultra 550B A55B 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 (moonshotai/kimi-k3.1-pro, nvidia/nemotron-3-ultra-550b-a55b).

Kimi K3.1 Pro vs Nemotron 3 Ultra 550B A55B

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

Estimate monthly cost for these models

Kimi K3.1 Pro MoonshotAImoonshotai/kimi-k3.1-pro

Nemotron 3 Ultra 550B A55B NVIDIAnvidia/nemotron-3-ultra-550b-a55b

Creator

MoonshotAI

NVIDIA

Released

Oct 23, 2026

May 16, 2026

Context window

1.05M

262K

Max output

1.05M

16K

Input / 1MLowest provider price

$2.00

$0.50

Output / 1MLowest provider price

$10.00

$2.20

Providers

IntelligenceArtificial Analysis index

46.5

11.8

Accepts

Text, Image

Text

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Kimi K3.1 Pro vs Nemotron 3 Ultra 550B A55B: summary

Kimi K3.1 Pro and Nemotron 3 Ultra 550B A55B are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Kimi K3.1 Pro, from MoonshotAI, has a 1,048,576-token context window, costs $2.00/1M input and $10.00/1M output tokens and scores 46.5 on the Artificial Analysis Intelligence Index.

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.

Nemotron 3 Ultra 550B A55B is the cheapest on input, 4× cheaper than the next model, Kimi K3.1 Pro has the largest context window and Kimi K3.1 Pro 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="moonshotai/kimi-k3.1-pro", messages=[...]) # or client.chat.completions.create(model="nvidia/nemotron-3-ultra-550b-a55b", messages=[...])

Full API docs

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More comparisons

Benchmark scores sourced from ArtificialAnalysis