Claude Fable 5 vs GPT 5.3 Codex
Anthropic's Mythos-class flagship for ambitious, long-running professional work.
OpenAI's most advanced agentic coding model with 400K context.
No captured outputs for these models yet.
Frequently Asked Questions: Claude Fable 5 vs GPT 5.3 Codex▼
Which is better, Claude Fable 5 or GPT 5.3 Codex?
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Based on the Capability Index, Claude Fable 5 scores higher (91.6 vs 87.0). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.
Which is cheaper, Claude Fable 5 or GPT 5.3 Codex?
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GPT 5.3 Codex has a lower blended cost. Claude Fable 5: $10.00 input / $50.00 output. GPT 5.3 Codex: $1.75 input / $14.00 output.
Which has a larger context window, Claude Fable 5 or GPT 5.3 Codex?
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Claude Fable 5 has a larger context window: Claude Fable 5 supports 1M tokens vs GPT 5.3 Codex at 400K tokens.
Do both Claude Fable 5 and GPT 5.3 Codex support vision?
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Yes, both Claude Fable 5 and GPT 5.3 Codex support vision/image input.
What are the key differences between Claude Fable 5 and GPT 5.3 Codex?
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Key differences: GPT 5.3 Codex is significantly cheaper. Compare full specs on this page.
Which model should I choose for my use case?
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If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Claude Fable 5 and GPT 5.3 Codex for free on idapt.app to see which performs better for your specific needs.