The Model Index
Models/OpenAI

GPT-5.3-Codex

OpenAIReleased 5 Feb 2026ClosedReasoning
170156–184Index score#18 · provisional, limited data
3/ 8Core tests taken2 of 6 areas · plus 1 anchor tests
FrontierVersus the frontier at releaseset or matched the record
$1.75/ $14Price per million tokensinput / output, list price
400KContext windowtokens it reads at once

Where it sitson the frontier

Among the first models to reach this score.

Test resultsby area · tick = best by any model

Reasoning & knowledgeno evidence yet
GPQA Diamond
no result
Humanity's Last Exam
no result
Mathsno evidence yet
FrontierMath T1-3
no result
Codingevidence
SWE-bench Verified
75%
Terminal-Bench
78%
Agentsno evidence yet
APEX-Agents
no result
Novel problemsno evidence yet
ARC-AGI-2
no result
Long tasksevidence
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 sayrank on each leaderboard

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 attop three 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 itprices checked 1 Oct 2026

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

Released5 Feb 2026
Announcementopenai.com ↗
Release entryGPT-5.3-Codex
Scored asGPT-5.3 Codex
Artificial Analysis index33 · xhigh (their estimate)
Output speed85 tokens/s
Hugging Faceclosed weights

OpenAI releasesaround this one