What is the difference between Claude Fable 5.1 and Nemotron 3 Ultra?

Claude Fable 5.1 is developed by Anthropic while Nemotron 3 Ultra is developed by NVIDIA. Claude Fable 5.1 has a 1.0M token context window vs Nemotron 3 Ultra's 1.0M. You can compare their actual outputs across 10 challenges on Rival to see how they differ in practice.

Which is better, Claude Fable 5.1 or Nemotron 3 Ultra?

It depends on your use case. Claude Fable 5.1 and Nemotron 3 Ultra each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 10 challenges so you can judge which fits your needs best.

How much does Claude Fable 5.1 cost compared to Nemotron 3 Ultra?

Claude Fable 5.1 costs $10/M input tokens and Nemotron 3 Ultra costs $0/M input tokens. Nemotron 3 Ultra is $10.00/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Claude Fable 5.1 and Nemotron 3 Ultra on Rival?

This page shows a side-by-side comparison of Claude Fable 5.1 and Nemotron 3 Ultra across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Updated Sep 2026

Claude Fable 5.1vsNemotron 3 Ultra

Nemotron 3 Ultra is cheaper than Claude Fable 5.1 at $0/M vs $10/M input tokens.

Claude Fable 5.1 and Nemotron 3 Ultra compared across 10 shared prompts
Spec	Claude Fable 5.1	Nemotron 3 Ultra
Input price	$10/M tokens	Free
Output price	$50/M tokens	Free
Context window	1.0M tokens	1.0M tokens
Weights	Closed	Open
Free API (OpenRouter)	No	Yes (1 provider)
Released	Sep 2026	Jun 2026

Our Verdict

Claude Fable 5.1

Nemotron 3 UltraRunner-up

Not enough votes to call it. On the specs, Claude Fable 5.1 has the edge: newer, major provider backing.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Fable 5.1

Input

$10.00

Output

$50.00

Nemotron 3 Ultra

Input

$0.000

Output

$0.000

Where to run it

5 hosts

Claude Fable 5.14 hosts

HostInOutContextUptime

Amazon Bedrock$10.00 in$50.00 out1M—Anthropic$10.00 in$50.00 out1M99.1% up Azure AI Foundry$10.00 in$50.00 out1M99.1% up Google Vertex AI$10.00 in$50.00 out1M99.8% up

Nemotron 3 Ultra1 host

HostInOutContextUptime

NVIDIA$0 in$0 out1M97.7% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Cost per 1M tokens

5 hosts

What we learned reading every model

Common questions

What is the difference between Claude Fable 5.1 and Nemotron 3 Ultra?

Which is better, Claude Fable 5.1 or Nemotron 3 Ultra?

How much does Claude Fable 5.1 cost compared to Nemotron 3 Ultra?

How can I compare Claude Fable 5.1 and Nemotron 3 Ultra on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Cost per 1M tokens

5 hosts

What we learned reading every model

Common questions

What is the difference between Claude Fable 5.1 and Nemotron 3 Ultra?

Which is better, Claude Fable 5.1 or Nemotron 3 Ultra?

How much does Claude Fable 5.1 cost compared to Nemotron 3 Ultra?

How can I compare Claude Fable 5.1 and Nemotron 3 Ultra on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages