What is the difference between Claude Fable 5.1 and GPT-5.4 Pro?

Claude Fable 5.1 is developed by Anthropic while GPT-5.4 Pro is developed by OpenAI. Claude Fable 5.1 has a 1.0M token context window vs GPT-5.4 Pro's 1.1M. You can compare their actual outputs across 1 challenges on Rival to see how they differ in practice.

Which is better, Claude Fable 5.1 or GPT-5.4 Pro?

It depends on your use case. Claude Fable 5.1 and GPT-5.4 Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 1 challenges so you can judge which fits your needs best.

How much does Claude Fable 5.1 cost compared to GPT-5.4 Pro?

Claude Fable 5.1 costs $10/M input tokens and GPT-5.4 Pro costs $30/M input tokens. Claude Fable 5.1 is $20.00/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 GPT-5.4 Pro on Rival?

This page shows a side-by-side comparison of Claude Fable 5.1 and GPT-5.4 Pro 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-5.4 Pro

Claude Fable 5.1 is cheaper than GPT-5.4 Pro at $10/M vs $30/M input tokens.

Claude Fable 5.1 and GPT-5.4 Pro compared across 1 shared prompts
Spec	Claude Fable 5.1	GPT-5.4 Pro
Input price	$10/M tokens	$30/M tokens
Output price	$50/M tokens	$180/M tokens
Context window	1.0M tokens	1.1M tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Sep 2026	Mar 2026

Our Verdict

Claude Fable 5.1

GPT-5.4 Pro

Not enough votes to call it. On the specs, nothing separates them.

Claude Fable 5.1 costs 3.6x 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

3.0× cheaper

Output

$50.00

3.6× cheaper

GPT-5.4 Pro

Input

$30.00

Output

$180.00

Claude Fable 5.1 is cheaper on both: 3.0× input, 3.6× 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-5.4 Pro2 hosts

HostInOutContextUptime

Azure AI Foundry$30.00 in$180.00 out1.1M—OpenAI$30.00 in$180.00 out1.1M97.6% up

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

Research

What we learned reading every model

FAQ

Common questions

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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-5.4 Pro?

Which is better, Claude Fable 5.1 or GPT-5.4 Pro?

How much does Claude Fable 5.1 cost compared to GPT-5.4 Pro?

How can I compare Claude Fable 5.1 and GPT-5.4 Pro 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-5.4 Pro?

Which is better, Claude Fable 5.1 or GPT-5.4 Pro?

How much does Claude Fable 5.1 cost compared to GPT-5.4 Pro?

How can I compare Claude Fable 5.1 and GPT-5.4 Pro on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages