Claude 3.5 Sonnet vs GPT-5.1 Codex
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.1 Codex by OpenAI wins on 13 of 14 benchmarks against Claude 3.5 Sonnet by Anthropic, which leads on 0. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, GPT-5.1 Codex scores 1395 on Chatbot Arena ELO compared to Claude 3.5 Sonnet's 1268, while GPT-5.1 Codex scores 82.0% on MMLU-Pro compared to Claude 3.5 Sonnet's 73.0%.
Coding: In coding, GPT-5.1 Codex scores 96.0% on HumanEval+ compared to Claude 3.5 Sonnet's 81.7%, while GPT-5.1 Codex scores 78.0% on SWE-bench Verified compared to Claude 3.5 Sonnet's 49.0%, while GPT-5.1 Codex scores 85.0% on LiveCodeBench compared to Claude 3.5 Sonnet's 38.0%.
Math: In math, GPT-5.1 Codex scores 85.0% on MATH compared to Claude 3.5 Sonnet's 78.3%, while GPT-5.1 Codex scores 95.0% on GSM8K compared to Claude 3.5 Sonnet's 91.0%.
Reasoning: In reasoning, GPT-5.1 Codex scores 65.0% on GPQA Diamond compared to Claude 3.5 Sonnet's 59.4%, while GPT-5.1 Codex scores 52.0% on ARC-AGI compared to Claude 3.5 Sonnet's 15.0%.
Context: In context, GPT-5.1 Codex scores 400K on Context Length compared to Claude 3.5 Sonnet's 200K.
Pricing Comparison
Claude 3.5 Sonnet costs $3.0/1M input tokens and $15.0/1M 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 3.5 Sonnet generates output at 70 tok/s compared to GPT-5.1 Codex's 85 tok/s, and the time to first token is 400 ms for Claude 3.5 Sonnet versus 400 ms for GPT-5.1 Codex. GPT-5.1 Codex delivers faster throughput.
Verdict
GPT-5.1 Codex leads across the board in coding, general intelligence, math, affordability, speed, making it the stronger overall choice in this comparison.
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Claude 3.5 Sonnet vs GPT-5.1 Codex — FAQ
Which is better, Claude 3.5 Sonnet or GPT-5.1 Codex?
GPT-5.1 Codex wins on more benchmarks overall (13 vs 0). However, the best choice depends on your specific needs — each model excels in different areas.
How does Claude 3.5 Sonnet compare to GPT-5.1 Codex for coding?
GPT-5.1 Codex is better for coding, scoring 78.0% on SWE-bench Verified compared to 49.0%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is Claude 3.5 Sonnet cheaper than GPT-5.1 Codex?
Yes, GPT-5.1 Codex is cheaper. Claude 3.5 Sonnet costs $3.0/1M input and $15.0/1M output tokens. GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output tokens.
Which is faster, Claude 3.5 Sonnet or GPT-5.1 Codex?
GPT-5.1 Codex is faster, generating output at 85 tok/s compared to 70 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Claude 3.5 Sonnet vs GPT-5.1 Codex comparison cover?
This comparison covers 14 benchmarks including Chatbot Arena ELO, MMLU-Pro, HumanEval+, MATH, GPQA Diamond, SWE-bench Verified, Output Speed, LiveCodeBench, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.