GPT-5.3-Codex vs o3
o3 is cheaper on output tokens, while GPT-5.3-Codex offers a larger context window. Choose GPT-5.3-Codex or o3 based on the trade-off between cost, context, and the benchmarks that matter for your use case.
| Spec | GPT-5.3-Codex | o3 |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input / 1M tokens | $1.75 | $2.00 |
| Output / 1M tokens | $14.00 | $8.00 |
| Context window | 400K | 200K |
| Parameters | — | — |
| Open weights | No | No |
| Released | Feb 2026 | Apr 2025 |
| LiveBench score | 73.2 | — |
| LMArena WebDev Elo score | 1407 | — |
| Aider Polyglot score | — | 81.3 |
| SWE-bench Verified score | — | 58.4 |
| GPQA Diamond score | — | 81.8 |
| FrontierMath score | — | 18.7 |
| Epoch Capabilities Index score | — | 147 |
| SWE-bench Multimodal score | — | 36.0 |
| LMArena (Chatbot Arena) Elo score | — | 1410 |
| LMArena Vision Elo score | — | 1214 |
FAQ
Is GPT-5.3-Codex or o3 cheaper?
o3 is cheaper on output tokens ($8.00 vs $14.00 per 1M).
Which has the larger context window, GPT-5.3-Codex or o3?
GPT-5.3-Codex has the larger context window (400K tokens).
Pricing is indicative — confirm with the provider before production use. Highlighted values indicate the better figure for that row.