GPT-5.3-Codex vs o3
o3 leads in 3 of 8 categories
Arena ELO
o3
Cheaper
GPT-5.3-Codex
Faster
o3
Detailed Comparison
| Category | GPT-5.3-Codex | o3 |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 128K | 200K WIN |
| Input Price ($/1M) | $1.75 WIN | $10 |
| Output Price ($/1M) | $14 WIN | $40 |
| Arena ELO | N/A | 1422 WIN |
| Coding | N/A | unknown |
| Reasoning | N/A | unknown |
| Speed (tokens/sec) | N/A | ~30 t/s WIN |
| Open Source | No | No |
Frequently Asked Questions
Which is cheaper, GPT-5.3-Codex or o3?
GPT-5.3-Codex is approximately 69% cheaper than o3 per million tokens.
Which is better for coding, GPT-5.3-Codex or o3?
GPT-5.3-Codex scores N/A on coding benchmarks, while o3 scores unknown.
Which has a larger context window?
GPT-5.3-Codex supports 128K context, while o3 supports 200K.
Is GPT-5.3-Codex or o3 open source?
GPT-5.3-Codex is proprietary. o3 is proprietary.
More Comparisons
GPT-5.3-Codex vs Claude Opus 4.5GPT-5.3-Codex vs Llama 4 ScoutGPT-5.3-Codex vs Claude Sonnet 4.6GPT-5.3-Codex vs Claude Haiku 4.5GPT-5.3-Codex vs GLM-5.2GPT-5.3-Codex vs Qwen 3.6GPT-5.3-Codex vs GPT-4oGPT-5.3-Codex vs DeepSeek R1o3 vs Claude Opus 4.5o3 vs Llama 4 Scouto3 vs Claude Sonnet 4.6o3 vs Claude Haiku 4.5o3 vs GLM-5.2o3 vs Qwen 3.6o3 vs GPT-4oo3 vs DeepSeek R1