OpenAI · Released Feb 5, 2026GPT-5.3 Codex
Coding-optimized GPT model for repository edits, reviews, and agentic software work.
- Capability
- 156.8ECI · #18 of 148
- Input
- $1.75per 1M tokens
- Output
- $14.00per 1M tokens
- Context
- 400K128K max output
What it costs
- Input
- $1.75per million tokens
- Output
- $14.00per million tokens
- Cached input
- $0.175per million tokens
- Blended (3:1)
- $4.81pricier than 87% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $10.50 |
| Team assistant25M input + 5M output tokens | $113.75 |
| Production app250M input + 50M output tokens | $1,138 |
Official OpenAI API price, as listed on models.dev.
Independent benchmarks
#18 of 148 scored models
The shaded band is Epoch AI’s confidence range (153.5–160.8); the tick marks the median scored model.
Scores from Epoch AI, run independently of OpenAI.
The details
- Lab
- OpenAI
- Released
- Feb 5, 2026
- Knowledge cutoff
- Aug 31, 2025
- Context window
- 400,000 tokens
- Max output
- 128,000 tokens
- Inputs
- Text, Images, PDFs
- Output
- Text
- Reasoning
- Adjustable effort low · medium · high · xhigh
- Tool calling
- Yes
- Structured output
- Yes
- Weights
- Proprietary
- API model ID
gpt-5.3-codexon OpenAI- Availability
- 19 API providerslisted on models.dev
What OpenAI claims
Published by the lab at launch. Settings vary, so compare these only with care.
More from OpenAI
About GPT-5.3 Codex
How much does GPT-5.3 Codex cost?
GPT-5.3 Codex costs $1.75 input / $14.00 output per million tokens (official OpenAI API price). Cached input is $0.175 per million tokens. At a 3:1 input-to-output mix that is $4.81 per million tokens, more expensive than 87% of the 360 priced models we track.
What is the context window of GPT-5.3 Codex?
GPT-5.3 Codex accepts up to 400,000 tokens per request and can write up to 128,000 tokens in one response.
How good is GPT-5.3 Codex?
Epoch AI gives GPT-5.3 Codex a Capabilities Index score of 156.8 (likely range 153.5–160.8), ranking it #18 of 148 models Epoch has scored. Epoch AI benchmark results: SWE-bench Verified 74.8%.
Is GPT-5.3 Codex open source?
No. GPT-5.3 Codex is proprietary; you use it through OpenAI’s API or partner platforms.
What inputs does GPT-5.3 Codex support?
GPT-5.3 Codex accepts text, images and PDFs and replies in text. It is a reasoning model with low, medium, high and xhigh effort settings, supports tool calling and can return structured JSON output.
When was GPT-5.3 Codex released?
OpenAI released GPT-5.3 Codex on Feb 5, 2026. Its training data runs to Aug 31, 2025.
What are the best alternatives to GPT-5.3 Codex?
The closest current models from other labs on capability, price and release date are Gemini 3.1 Pro Preview (Google, ECI 154.8, $2.00 / $12.00), Claude Sonnet 5 (Anthropic, ECI 156.3, $2.00 / $10.00), Kimi K3 (Moonshot AI, ECI 157.6, $3.00 / $15.00) and Qwen3.8 Max (Alibaba (Qwen), ECI 156.6, $2.00 / $6.00).