ChatGPT-4o (March 2025) vs 
Claude Fable 5.1
ChatGPT-4o (March 2025) is cheaper than Claude Fable 5.1 at $5/M vs $10/M input tokens.
Mario Level UI Recreation
Playable Mario level in one HTML file. The physics is the hard part.
Loading the build
Loading the build
Which answer wins?
Price and specs
Not enough votes to call it. On the specs, Claude Fable 5.1 has the edge: newer, bigger context window. ChatGPT-4o (March 2025) costs 3.3x less per token.
| Spec | ChatGPT-4o (March 2025) | Claude Fable 5.1 |
|---|---|---|
| Input price | $5/M tokens | $10/M tokens |
| Output price | $15/M tokens | $50/M tokens |
| Context window | 128K tokens | 1.0M tokens |
| Weights | — | Closed |
| Free API (OpenRouter) | No | No |
| Released | Mar 2025 | Sep 2026 |
| At 10M a month | $50.00 | $100 |
Input tokens at list price. No caching, no batch discount.
Where to run it
ChatGPT-4o (March 2025)
No hosts listed on OpenRouter.
Per million tokens. Prices and uptime via OpenRouter, checked 7 Oct 2026.
Common questions
What is the difference between ChatGPT-4o (March 2025) and Claude Fable 5.1?
ChatGPT-4o (March 2025) is developed by OpenAI while Claude Fable 5.1 is developed by Anthropic. ChatGPT-4o (March 2025) has a 128K token context window vs Claude Fable 5.1's 1.0M. You can compare their actual outputs across 4 challenges on Rival to see how they differ in practice.
Which is better, ChatGPT-4o (March 2025) or Claude Fable 5.1?
It depends on your use case. ChatGPT-4o (March 2025) and Claude Fable 5.1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 4 challenges so you can judge which fits your needs best.
How much does ChatGPT-4o (March 2025) cost compared to Claude Fable 5.1?
ChatGPT-4o (March 2025) costs $5/M input tokens and Claude Fable 5.1 costs $10/M input tokens. ChatGPT-4o (March 2025) is $5.00/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 ChatGPT-4o (March 2025) and Claude Fable 5.1 on Rival?
This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Claude Fable 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.
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