Claude Sonnet 4 vs GPT-5.1-Codex
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Claude Sonnet 4 and GPT-5.1-Codex.
Claude Sonnet 4
Claude Sonnet 4 significantly enhances the capabilities of its predecessor, Sonnet 3.7, excelling in both coding and reasoning tasks with improved precision and controllability. Achieving state-of-the-art performance on SWE-bench (72.7%),...
GPT-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....
Technical Specifications
| Specification | Claude Sonnet 4 | GPT-5.1-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context Window | 1,000,000 tokens | 400,000 tokens |
| Agent Suitability | N/A | N/A |
| Time to First Token (TTFT) | N/A | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | beta | stable |
| API Available | Yes | Yes |
| Released Date | 2025-05-22 | 2025-11-13 |
API Pricing Comparison
Input Price per Million Tokens
Claude Sonnet 4
$3.00
GPT-5.1-Codex
$1.25
Output Price per Million Tokens
Claude Sonnet 4
$15.00
GPT-5.1-Codex
$10.00
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Claude Sonnet 4 Quirks & Gotchas
No developer gotchas reported.
GPT-5.1-Codex Quirks & Gotchas
No developer gotchas reported.