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AnthropicClaude Fable 5VSOpenAIGPT-5.4

Analysis by:the whichllmmodel Editorial Team|Updated: June 2026

Our Take

We recommend Claude Fable 5 if your workflow requires peak coding capability, or the 3.6x cheaper GPT-5.4 to optimize your API budget. While both models deliver similar reasoning performance, Claude Fable 5 holds a clear lead in coding. Choose Claude Fable 5 for complex development tasks, or GPT-5.4 for cost optimization.
WHY?
Benchmark Calculations & Evidence:
  • Coding Benchmarks: Both models were evaluated on the SWE-bench Pro benchmark. Claude Fable 5 scored 80.3%, while GPT-5.4 scored 57.7%.
  • Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. Claude Fable 5 scored 94.1%, while GPT-5.4 scored 92.8%.
  • Cost Efficiency: GPT-5.4 pricing ($2.5/M input, $15/M output) is 3.6x cheaper than Claude Fable 5 ($10/M input, $50/M output).
  • Was this recommendation helpful?
    Model Specs

    Claude Fable 5

    Benchmarks & Scores

    Coding (swe-bench-pro)Winner (+22.6%)
    80.3%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)Winner (+1.3%)
    94.1%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)
    $20.00Input: $10.00 | Output: $50.00
    Context Window
    1.05M tokens
    Model Specs

    GPT-5.4

    Benchmarks & Scores

    Coding (swe-bench-pro)
    57.7%

    complex codebases, multi-file repositories, and architectural planning

    Reasoning (gpqa-diamond)
    92.8%

    graduate-level science QA

    Cost & Context

    Cost (per 1M tokens)3.6x cheaper
    $5.63Input: $2.50 | Output: $15.00
    Context WindowLarger
    1.05M tokens

    Frequently Asked Questions about Claude Fable 5 vs GPT-5.4

    GPT-5.4 is cheaper than Claude Fable 5. GPT-5.4 has a blended cost of $5.63/1M tokens, which is about 3.6x cheaper than Claude Fable 5 at $20.00/1M tokens.

    Claude Fable 5 is better for coding tasks on this benchmark. It scores 80.3% on swe-bench-pro (complex codebases, multi-file repositories, and architectural planning) compared to GPT-5.4 which scores 57.7%.

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