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Map / Core AI / Foundation Models / ChatGPT / o-series

OpenAI o-series

by OpenAI · part of ChatGPT · Text

OpenAI's separate reasoning-model line (o1, o3, o4-mini) from 2024-25, succeeded by GPT-5 and now being retired.

Retired

23 Oct 2026The last version was o-series 4, from 16 Apr 2025

Versions

3since OpenAI o1 in December 2024

All versions

VersionReleasedAfter previousStatusComes asSource
OpenAI o4-mini16 Apr 20250 daysRetiredo4-mini-deep-researchdevelopers.openai.com
OpenAI o316 Apr 2025132 daysDeprecatedo3-minio3-proo3-deep-researchdevelopers.openai.com
OpenAI o15 Dec 2024FirstRetiredo1-previewo1-minio1-proopenai.com

Dates from OpenAI's own announcements; each row links to its source.

The ChatGPT family

2023202420252026TodayAstraGPT-6 Astra, 3 Sep 20266SolGPT-4, 14 Mar 20234GPT-4 Turbo, 9 Apr 2024GPT-4o, 13 May 20244oGPT-4.5, 27 Feb 2025, previewGPT-4.1, 14 Apr 20254.1GPT-5, 7 Aug 20255GPT-5.1, 12 Nov 2025GPT-5.2, 11 Dec 20255.2GPT-5.4, 5 Mar 2026GPT-5.5, 23 Apr 20265.5GPT-5.6 Sol, 9 Jul 20265.6GPT-6 Sol, 22 Sep 2026GPT-6.1 Sol, 29 Sep 20266.1TerraGPT-4o mini, 18 Jul 20244oGPT-4.1 mini, 14 Apr 20254.1GPT-5 mini, 7 Aug 20255GPT-5.4 mini, 17 Mar 20265.4GPT-5.6 Terra, 9 Jul 20265.6LunaGPT-4.1 nano, 14 Apr 20254.1GPT-5 nano, 7 Aug 20255GPT-5.4 nano, 17 Mar 20265.4GPT-5.6 Luna, 9 Jul 20265.6GPT-6 Luna, 22 Sep 20266o-seriesOpenAI o1, 5 Dec 20241OpenAI o3, 16 Apr 2025OpenAI o4-mini, 16 Apr 20254

VersionPreviewLatest version

Questions

What is the latest version of OpenAI o-series?

OpenAI o-series was retired on 23 Oct 2026. Its last version was OpenAI o4-mini, released on 16 Apr 2025.

When was OpenAI o3 released?

OpenAI o3 came out on 16 Apr 2025.

When was OpenAI o1 released?

OpenAI o1 came out on 5 Dec 2024.