> GPT-5.3-Codex is a closed AI model from OpenAI, released 5 Feb 2026. Index score 170 (GPT-4 = 100), rank 18 of 229 ranked models. API price $1.75 in / $14 out per million tokens, 400K context.

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# GPT-5.3-Codex

OpenAI

Released 5 Feb 2026

Closed

Reasoning

[Compare](https://themodelindex.org/compare/gpt-5-3-codex-vs-kimi-k2-5/) [Announcement](https://openai.com/ja-JP/index/introducing-gpt-5-3-codex/)

170156–184

Index score

#18 · provisional, limited data

3/ 8

Core tests taken

2 of 6 areas · plus 1 anchor tests

Frontier

Versus the frontier at release

set or matched the record

$1.75/ $14

Price per million tokens

input / output, list price

400K

Context window

tokens it reads at once

## Where it sits · on the frontier

_Chart: Model Index score of every scored model since late 2022, with the best closed and best open model over time_

Among the first models to reach this score.

## Test results · by area · tick = best by any model

Show 1 anchor tests

Reasoning & knowledge

no evidence yet

GPQA Diamond

no result

Humanity's Last Exam

no result

Maths

no evidence yet

FrontierMath T1-3

no result

Coding

evidence

SWE-bench Verified

75%

Terminal-Bench

78%

Agents

no evidence yet

APEX-Agents

no result

Novel problems

no evidence yet

ARC-AGI-2

no result

Long tasks

evidence

METR time horizon

5.8 h

Independent results from the Epoch AI benchmarking hub, best reasoning setting. The core tests are shown here; anchor tests also inform the score and can be shown above.

## What others say · rank on each leaderboard

The Model Index

independent tests, our method

#18

of 219 · 170

Epoch Capabilities Index

overall capability from many benchmarks

#18

of 239 · 156.8

Artificial Analysis Intelligence Index

overall capability across ten evaluations

#28

of 207 · 33

LMArena · WebDev

building web apps and front ends

#74

of 123 · 1408

Further left is better. Leaderboards measure different things: LMArena is people voting blind between two answers, the others are test scores. Click any row for the source.

## Best at · top three among current models

2nd

SWE-bench Verified

Epoch AI · independent

2nd

Terminal-Bench

Epoch AI · independent

2nd

METR time horizon

Epoch AI · independent

Where this model places in the top three of today's models, on category leaderboards and on our core tests.

## Where to use it · prices checked 1 Oct 2026

#### From the lab

ChatGPT

app · subscription

↗

OpenAI API

API

↗

#### API providers · 2 · per million tokens, in / out

A

Azure

$1.75 / $14

cheapest

O

OpenAI

$3.5 / $28

↗

Provider prices come from OpenRouter's live listing; going direct to a provider can differ. Subscriptions are the lab's own apps.

## Facts and sources

Released

5 Feb 2026

Announcement

[openai.com ↗](https://openai.com/ja-JP/index/introducing-gpt-5-3-codex/)

Release entry

GPT-5.3-Codex

Scored as

GPT-5.3 Codex

Artificial Analysis index

33 · xhigh (their estimate)

Output speed

85 tokens/s

Hugging Face

closed weights

## OpenAI releases · around this one

GPT-5.2

Closed

11 DEC 2025

index 162

GPT-5.2-Codex

Closed

18 DEC 2025

GPT-5.3-Codex

Closed

5 FEB 2026

index 170

GPT-5.3-Codex-Spark

Closed

12 FEB 2026

GPT-5.4 Thinking

Closed

5 MAR 2026

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Source: https://themodelindex.org/models/gpt-5-3-codex/ · The Model Index · data as of 2026-10-01