Claude Fable 5 vs GPT-5.1 Codex
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
Claude Fable 5 by Anthropic and GPT-5.1 Codex by OpenAI are evenly matched across 10 benchmarks. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
Coding: In coding, Claude Fable 5 scores 95.0% on SWE-bench Verified compared to GPT-5.1 Codex's 78.0%, while Claude Fable 5 scores 1334 on Design Arena ELO compared to GPT-5.1 Codex's 1197, while Claude Fable 5 scores 1309 on Website Arena ELO compared to GPT-5.1 Codex's 1174.
Reasoning: In reasoning, Claude Fable 5 scores 83.8% on GPQA Diamond compared to GPT-5.1 Codex's 65.0%.
Context: In context, Claude Fable 5 scores 1.0M on Context Length compared to GPT-5.1 Codex's 400K.
Pricing Comparison
Claude Fable 5 costs $10.0/1M input tokens and $50.0/1M output tokens, while GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output. GPT-5.1 Codex is the more affordable option for API usage.
Speed Comparison
Claude Fable 5 generates output at 60 tok/s compared to GPT-5.1 Codex's 85 tok/s, and the time to first token is 81680 ms for Claude Fable 5 versus 400 ms for GPT-5.1 Codex. GPT-5.1 Codex delivers faster throughput.
Verdict
For developers prioritizing coding, Claude Fable 5 has the edge. For those who value affordability and speed, GPT-5.1 Codex is the stronger choice.
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Claude Fable 5 vs GPT-5.1 Codex — FAQ
Which is better, Claude Fable 5 or GPT-5.1 Codex?
Claude Fable 5 and GPT-5.1 Codex are evenly matched across benchmarks. The best choice depends on your specific priorities such as coding ability, speed, or pricing.
How does Claude Fable 5 compare to GPT-5.1 Codex for coding?
Claude Fable 5 is better for coding, scoring 95.0% on SWE-bench Verified compared to 78.0%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is Claude Fable 5 cheaper than GPT-5.1 Codex?
Yes, GPT-5.1 Codex is cheaper. Claude Fable 5 costs $10.0/1M input and $50.0/1M output tokens. GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output tokens.
Which is faster, Claude Fable 5 or GPT-5.1 Codex?
GPT-5.1 Codex is faster, generating output at 85 tok/s compared to 60 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Claude Fable 5 vs GPT-5.1 Codex comparison cover?
This comparison covers 10 benchmarks including SWE-bench Verified, GPQA Diamond, Output Speed, Time to First Token, Input Cost, Output Cost, Context Length, Cached Input Cost, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.