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Claude Fable 5 vs GPT 5.3 Codex

At a glance

Anthropic's Mythos-class flagship for ambitious, long-running professional work.

921M ctx$10.00/$50.00 per M#2/92

OpenAI's most advanced agentic coding model with 400K context.

87400K ctx$1.75/$14.00 per M#8/92
Demos
All demos

No shared demos for these models yet.

AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
Reasoning
CodingInsufficient data
AgenticInsufficient data
ReasoningInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Smarter5%
Capability
CapabilityECI5%91.6
Reasoning & Knowledge
Factual Recall68.3%
Math
Competition Math99.7%
Coding
Real-World Coding—
Agentic
Terminal Tasks—Task Horizon—
Reasoning
ReasoningInsufficient data
MathInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Cheaper76%
Capability
CapabilityECI87.0
Reasoning & Knowledge
Factual Recall—
Math
Competition Math—
Coding
Real-World Coding74.8%
Agentic
Terminal Tasks78.4%Task Horizon5.8h
Specs
1M
Context
128K
Max output
Jun 2026
Released
400K
Context
128K
Max output
Feb 2026
Released
Capabilities
Vision
Audio
Reasoning
Vision
Audio
Reasoning
Pricing
Live pricing, shown before you run
Input$10.00/M tokens
Output$50.00/M tokens
Cache read$1.00/M tokens
Cache write$12.50/M tokens
Web search$0.01/search
Live pricing, shown before you run
Input83%$1.75/M tokens
Output72%$14.00/M tokens
Cache read83%$0.17/M tokens
Web search$0.01/search
Chat with Claude Fable 5Go to model
Chat with GPT 5.3 CodexGo to model
Frequently Asked Questions: Claude Fable 5 vs GPT 5.3 Codex▼

Which is better, Claude Fable 5 or GPT 5.3 Codex?

▼

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?

▼

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?

▼

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?

▼

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?

▼

Key differences: GPT 5.3 Codex is significantly cheaper. Compare full specs on this page.

Which model should I choose for my use case?

▼

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.

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