What is the difference between Claude Sonnet 4.5 and GPT-5 Pro?

Claude Sonnet 4.5 is developed by Anthropic while GPT-5 Pro is developed by OpenAI. Claude Sonnet 4.5 has a 200K token context window vs GPT-5 Pro's 400K. You can compare their actual outputs across 36 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 4.5 or GPT-5 Pro?

It depends on your use case. Claude Sonnet 4.5 and GPT-5 Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 36 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 4.5 cost compared to GPT-5 Pro?

Claude Sonnet 4.5 costs $3/M input tokens and GPT-5 Pro costs $15/M input tokens. Claude Sonnet 4.5 is $12.00/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 Sonnet 4.5 and GPT-5 Pro on Rival?

This page shows a side-by-side comparison of Claude Sonnet 4.5 and GPT-5 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 Oct 2025

Claude Sonnet 4.5vsGPT-5 Pro

Claude Sonnet 4.5 is cheaper than GPT-5 Pro at $3/M vs $15/M input tokens.

Claude Sonnet 4.5 and GPT-5 Pro compared across 36 shared prompts
Spec	Claude Sonnet 4.5	GPT-5 Pro
Input price	$3/M tokens	$15/M tokens
Output price	$15/M tokens	$120/M tokens
Context window	200K tokens	400K tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Sep 2025	Oct 2025
SWE-bench Verified	77.2%	74.9%

Our Verdict

GPT-5 Pro

Claude Sonnet 4.5Runner-up

Not enough votes to call it. On the specs, GPT-5 Pro has the edge: bigger model tier, bigger context window.

Pick Claude Sonnet 4.5 for Web Design, Conversation, Analysis. Pick GPT-5 Pro for Reasoning, Image Generation. Claude Sonnet 4.5 costs 8.0x less per token.

Too close to call

API pricing