OpenAI
GPT-5.3-Codex
GPT-5.3-Codex is a OpenAI model with 400K context, $1.75 in / $14 out per million tokens, last verified September 3, 2026. Open weights: no. Public-board scores are linked to the publisher; vendor-only figures stay in the watch-out, not on the board.
GPT-5.3-Codex is OpenAI's coding-specialised model powering the Codex agent at $1.75/$14.
Catalog record checked September 3, 2026Individual provider fields may change
| Specification | GPT-5.3-Codex |
|---|---|
| Provider | OpenAI |
| Tier | Frontier |
| Context window | 400K |
| Max output | 128K |
| Input / 1M tokens | $1.75 |
| Output / 1M tokens | $14 |
| Weights | Closed |
| Parameters | Not disclosed |
| Reasoning levels | none, low, medium, high, xhigh, max |
| Modalities | text, image |
| API model id | gpt-5.3-codex |
| Released | February 5, 2026 |
Pricing tiers: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent.
Verified evidence
Published benchmark results
Each result keeps its source and measurement date visible. A missing benchmark is not treated as a zero.
| Benchmark | Score | Measured | Source |
|---|---|---|---|
| Artificial Analysis Intelligence Index [high] | 52 | 2026-08-14 | Artificial Analysis · View source |
Best for
- Autonomous coding
- Repo-scale refactors
- Test generation
Watch out
Source receipts
Catalog figures for this model were checked against the following sources.
- OpenAI — Introducing GPT-5.3-Codex (accessed 2026-08-29)
- OpenAI API pricing (gpt-5.3-codex $1.75/$14) (accessed 2026-08-29)
Common questions
GPT-5.3-Codex
Answered from the verified figures on this page rather than general guidance.
How much does GPT-5.3-Codex cost per million tokens?
GPT-5.3-Codex is listed at $1.75 per million input tokens and $14 per million output tokens at standard rates. Output tokens usually dominate real bills, so weigh the output rate more heavily than the input rate. Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent.
What is GPT-5.3-Codex's context window?
GPT-5.3-Codex accepts about 400K tokens of context. That only matters if you routinely send very long documents, large codebases, or multi-turn histories that approach that limit.
What is GPT-5.3-Codex best for?
GPT-5.3-Codex is a frontier tier from OpenAI. It suits autonomous coding, repo-scale refactors, test generation. Tuned for coding, not general chat; use GPT-5.6 for broad reasoning.