Claude Opus 4.5 vs GPT-5.3-Codex
Claude Opus 4.5 leads in 3 of 8 categories
Arena ELO
Claude Opus 4.5
Cheaper
GPT-5.3-Codex
Faster
Claude Opus 4.5
Detailed Comparison
| Category | Claude Opus 4.5 | GPT-5.3-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context Window | 200K WIN | 128K |
| Input Price ($/1M) | $5 | $1.75 WIN |
| Output Price ($/1M) | $25 | $14 WIN |
| Arena ELO | 1380 WIN | N/A |
| Coding | 80.9% SWE-bench | N/A |
| Reasoning | unknown | N/A |
| Speed (tokens/sec) | ~35 t/s WIN | N/A |
| Open Source | No | No |
Frequently Asked Questions
Which is cheaper, Claude Opus 4.5 or GPT-5.3-Codex?
GPT-5.3-Codex is approximately 48% cheaper than Claude Opus 4.5 per million tokens.
Which is better for coding, Claude Opus 4.5 or GPT-5.3-Codex?
Claude Opus 4.5 scores 80.9% SWE-bench on coding benchmarks, while GPT-5.3-Codex scores N/A.
Which has a larger context window?
Claude Opus 4.5 supports 200K context, while GPT-5.3-Codex supports 128K.
Is Claude Opus 4.5 or GPT-5.3-Codex open source?
Claude Opus 4.5 is proprietary. GPT-5.3-Codex is proprietary.
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