> GPT-5-Codex is a closed AI model from OpenAI, released 15 Sep 2025.

[Models](https://themodelindex.org/models/) /[OpenAI](https://themodelindex.org/labs/openai/)

# GPT-5-Codex

OpenAI

Released 15 Sep 2025

Closed

Reasoning

Date verified

[Compare](https://themodelindex.org/compare/gpt-5-codex-vs-deepseek-v3-2-exp/) [Announcement](https://openai.com/index/introducing-upgrades-to-codex/)

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Index score

Not yet evaluated independently

1/ 8

Core tests taken

1 of 6 areas · plus 0 anchor tests

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Versus the frontier at release

Replaced by [GPT-5.1-Codex](https://themodelindex.org/models/gpt-5-1-codex/)

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Price per million tokens

no public API price found

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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_

GPT-5 reached this score 1 month earlier.

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

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

no result

Terminal-Bench

44%

Agents

no evidence yet

APEX-Agents

no result

Novel problems

no evidence yet

ARC-AGI-2

no result

Long tasks

no evidence yet

METR time horizon

no result

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

Not on any of the rankings we follow yet.

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

Replaced by GPT-5.1-Codex; it no longer leads any category among current models.

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

↗

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

15 Sep 2025

Announcement

[openai.com ↗](https://openai.com/index/introducing-upgrades-to-codex/)

Release entry

GPT-5-Codex

Scored as

GPT-5-Codex

Artificial Analysis index

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Output speed

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Hugging Face

closed weights

## OpenAI releases · around this one

gpt-oss-20b

Open

5 AUG 2025

index 128

GPT-5

Closed

7 AUG 2025

index 154

GPT-5-Codex

Closed

15 SEP 2025

GPT-5.1

Closed

12 NOV 2025

index 153

GPT-5.1-Codex-Max

Closed

19 NOV 2025

index 157

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