GPT
OpenAI's flagship generative line, from GPT-1 in 2018 to GPT-6 Astra; the o-series reasoning models merged into it in 2025 and `gpt-oss` carries the open weights.
At a glance
Current release
From the release row GPT-6 Astra. Prompts of up to 272K input tokens; above that, input is 2x and output 1.5x ($20 / $75). Batch and Flex are half price.
Family record: Official documentation · 5 Sep 2026
Built on it
4 products in this catalogue name this family on their own pages.
-
Fireworks AI
Fireworks AI
Official documentation · 5 Sep 2026 -
OpenAI API
OpenAI
Official documentation · 5 Sep 2026 -
SambaCloud
SambaNova
Official documentation · 5 Sep 2026 -
Together Inference
Together AI
Official documentation · 5 Sep 2026
Releases
-
GPT-1
Code and model for the paper 'Improving Language Understanding by Generative Pre-Training', the first generative pre-trained Transformer; the paper itself carries no date.
-
GPT-2
Paper 'Language Models are Unsupervised Multitask Learners' with a staged release: only a smaller model was made public at launch over misuse concerns.
-
GPT-3
Paper 'Language Models are Few-Shot Learners': 175 billion parameters, 10x any previous non-sparse model, learning tasks from text demonstrations without fine-tuning.
-
GPT-4
Accepts image and text input; OpenAI said it passes a simulated bar exam around the top 10% of test takers. ChatGPT (GPT-3.5) had launched Nov 2022; GPT-4 Turbo followed Nov 2023.
-
GPT-4o
Described by OpenAI as 'our fastest and most affordable flagship model'; GPT-4o mini, a small model for lightweight tasks, followed on Jul 18, 2024.
-
o1
o-series, not GPT-numbered: o1-preview and o1-mini, 'trained with reinforcement learning' to reason before answering; the full o1 reached the API on Dec 17, 2024.
-
GPT-4.1
gpt-4.1, gpt-4.1-mini and gpt-4.1-nano added to the API; preceded by the GPT-4.5 research preview released Feb 27, 2025.
-
o3
o-series: o3 and o4-mini launched together in the API; o3-mini had preceded them on Jan 31, 2025.
-
gpt-oss
gpt-oss-120b (117B params, 5.1B active) and gpt-oss-20b (21B, 3.6B active), Apache 2.0, text-only reasoning models with adjustable reasoning effort and 128K context.
-
GPT-5
gpt-5, gpt-5-mini and gpt-5-nano in the API; 400K context, text and image in. GPT-5 Pro (Oct 6), GPT-5.1 (Nov 13) and GPT-5.2 (Dec 11, 2025) were later flagships in the family.
-
GPT-5.4
'Our newest frontier model for professional work' with a 1,050,000-token context; GPT-5.4 mini and nano followed Mar 17 and GPT-5.5 / GPT-5.5 Pro on Apr 24, 2026.
-
GPT-5.6
A named family rather than tiers: GPT-5.6 Sol (frontier), Terra and Luna, plus GPT-5.6 Cyber; Sol has a 1,050,000-token context with text and image input.
-
GPT-6 Astra
'Our most capable model, built for the hardest end-to-end work'; 1,050,000-token context, reasoning effort low to max, rolling out first to Trusted Access Program enterprises.