AnthropicClaude Fable 5VSOpenAIGPT-5.5
Our Take
We recommend Claude Fable 5 if your workflow requires peak coding capability, or the 1.8x cheaper GPT-5.5 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-5.5 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-5.5 scored 58.6%.
Reasoning Benchmarks: Both models were evaluated on the GPQA Diamond benchmark. Claude Fable 5 scored 94.1%, while GPT-5.5 scored 93.6%.
Cost Efficiency: GPT-5.5 pricing ($5/M input, $30/M output) is 1.8x cheaper than Claude Fable 5 ($10/M input, $50/M output).
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Benchmarks & Scores
Coding (swe-bench-pro)Winner (+21.7%)
80.3%complex codebases, multi-file repositories, and architectural planning
Reasoning (gpqa-diamond)Winner (+0.5%)
94.1%graduate-level science QA
Cost & Context
Cost (per 1M tokens)
$20.00Input: $10.00 | Output: $50.00Context Window
1.05M tokensBenchmarks & Scores
Coding (swe-bench-pro)
58.6%complex codebases, multi-file repositories, and architectural planning
Reasoning (gpqa-diamond)
93.6%graduate-level science QA
Cost & Context
Cost (per 1M tokens)1.8x cheaper
$11.25Input: $5.00 | Output: $30.00Context WindowLarger
1.05M tokensFrequently Asked Questions about Claude Fable 5 vs GPT-5.5
GPT-5.5 is cheaper than Claude Fable 5. GPT-5.5 has a blended cost of $11.25/1M tokens, which is about 1.8x 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-5.5 which scores 58.6%.
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