What is the difference between Claude Fable 5.1 and GPT-5.1?

Claude Fable 5.1 is developed by Anthropic while GPT-5.1 is developed by OpenAI. Claude Fable 5.1 has a 1.0M token context window vs GPT-5.1's 400K. You can compare their actual outputs across 8 challenges on Rival to see how they differ in practice.

Which is better, Claude Fable 5.1 or GPT-5.1?

It depends on your use case. Claude Fable 5.1 and GPT-5.1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 8 challenges so you can judge which fits your needs best.

How much does Claude Fable 5.1 cost compared to GPT-5.1?

Claude Fable 5.1 costs $10/M input tokens and GPT-5.1 costs $1.25/M input tokens. GPT-5.1 is $8.75/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 GPT-5.1 on Rival?

This page shows a side-by-side comparison of Claude Fable 5.1 and GPT-5.1 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 5.1vsGPT-5.1

GPT-5.1 is cheaper than Claude Fable 5.1 at $1.25/M vs $10/M input tokens.

Claude Fable 5.1 and GPT-5.1 compared across 8 shared prompts
Spec	Claude Fable 5.1	GPT-5.1
Input price	$10/M tokens	$1.25/M tokens
Output price	$50/M tokens	$10/M tokens
Context window	1.0M tokens	400K tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Sep 2026	Nov 2025

Our Verdict

Claude Fable 5.1

GPT-5.1Runner-up

Not enough votes to call it. On the specs, Claude Fable 5.1 has the edge: newer, bigger context window.

GPT-5.1 costs 5.0x less per token.

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

GPT-5.1

Input

$1.25

8.0× cheaper

Output

$10.00

5.0× cheaper

GPT-5.1 is cheaper on both: 8.0× input, 5.0× output.

Where to run it

6 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

GPT-5.12 hosts

HostInOutContextUptime

Azure AI Foundry$1.25 in$10.00 out400k100% up OpenAI$1.25 in$10.00 out400k99.9% 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

6 hosts

What we learned reading every model

Common questions

What is the difference between Claude Fable 5.1 and GPT-5.1?

Which is better, Claude Fable 5.1 or GPT-5.1?

How much does Claude Fable 5.1 cost compared to GPT-5.1?

How can I compare Claude Fable 5.1 and GPT-5.1 on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Cost per 1M tokens

6 hosts

What we learned reading every model

Common questions

What is the difference between Claude Fable 5.1 and GPT-5.1?

Which is better, Claude Fable 5.1 or GPT-5.1?

How much does Claude Fable 5.1 cost compared to GPT-5.1?

How can I compare Claude Fable 5.1 and GPT-5.1 on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages