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GPT (ChatGPT / OpenAI) models

Version comparison

Last verified Oct 24, 2026. Figures that could not be confirmed on an official vendor page are marked unverified — we do not guess.

Full GPT (ChatGPT / OpenAI) comparison

Which one should I use?

  • In the ChatGPT app, what you can pick depends on the plan. OpenAI’s help center: GPT-6 Pro (powered by GPT-6 Astra) is on Pro, Business, and Enterprise; Plus gets Astra in ChatGPT Work and Codex, not as GPT-6 Pro in regular Chat. Free and Go do not get Astra.
  • For API work, OpenAI currently tells developers to start with GPT-6 Astra for hard jobs, GPT-6.1 Sol when you want similar quality for less money, and GPT-6 Luna for cheap high-volume work.
  • GPT-5.5 is the previous flagship. Use it only if your API work already depends on it.

GPT-6 Astra

Current
Context
1.05M
Max output
128K
API input / 1M
$10 / 1M
API output / 1M
$50 / 1M

Best for: Paid ChatGPT users and API developers with the hardest work — research, long coding, and multi-step computer use.

ChatGPT Plus: Astra in Work and Codex. Pro $100/$200, Business, and Enterprise: GPT-6 Pro in Chat (workspace permissions may apply). Not on Free or Go.

Source: GPT-6 Astra model page

GPT-6.1 Sol

Current
Context
1.05M
Max output
128K
API input / 1M
$2 / 1M
API output / 1M
$10 / 1M

Best for: API and ChatGPT Work/Codex users who want strong results without Astra’s price.

OpenAI help: GPT-6.1 Sol is a ChatGPT Work and Codex model, not regular Chat. It is rolling out on eligible paid plans; exact plan list depends on rollout and workspace settings.

Source: GPT-6.1 Sol model page

GPT-6 Sol

Current
Context
1.05M
Max output
128K
API input / 1M
$2 / 1M
API output / 1M
$10 / 1M

Best for: Existing API work built on GPT-6 Sol; new work should start on GPT-6.1 Sol.

OpenAI's ChatGPT docs list GPT-6 Sol for ChatGPT Work and Codex on paid plans. OpenAI's pages disagree on whether it also powers regular Chat, so check your model picker.

Source: GPT-6 Sol model page

GPT-6 Luna

Current
Context
1.05M
Max output
128K
API input / 1M
$0.1 / 1M
API output / 1M
$0.5 / 1M

Best for: Lots of short, cheap jobs — classification, drafts, and bulk API calls.

OpenAI help: GPT-6 Luna is a ChatGPT Work and Codex model, not regular Chat. Free/Go ChatGPT model names in the main Chat picker are a separate list (unverified here beyond the GPT-6 help article).

Source: GPT-6 Luna model page

GPT-5.5

Prior gen
Context
1.05M
Max output
128K
API input / 1M
$5 / 1M
API output / 1M
$30 / 1M

Best for: Existing API integrations that are not ready to move to GPT-6.

Retired from ChatGPT, ChatGPT Work and Codex on 14 Oct 2026. API access is unaffected.

Source: GPT-5.5 model page

GPT-6 Astra

Paid ChatGPT users and API developers with the hardest work — research, long coding, and multi-step computer use.

  • OpenAI’s current flagship for hard reasoning, coding, and computer-use jobs.
  • 1.05 million token context window and 128k max output on the API.
  • Built-in tools on the Responses API (search, files, computer use, and more).

Caveats

  • Most expensive current GPT listed here ($10 / $50 per 1M tokens on the API).
  • Plus does not include GPT-6 Pro in regular Chat — only Work and Codex.
  • Long prompts (over 272k input tokens) cost more per token.

Standard, short-context. Prompts over 272k input tokens are billed at 2× input and 1.5× output for the full request.

GPT-6.1 Sol

API and ChatGPT Work/Codex users who want strong results without Astra’s price.

  • OpenAI describes it as near-Astra quality at a lower API price ($2 / $10 per 1M).
  • Same 1.05M context and 128k max output as Astra.
  • Supports Fast and Ultrafast API modes (Ultrafast is priced higher).

Caveats

  • Not in regular ChatGPT conversations, per OpenAI’s Work and Codex help article.
  • Ultrafast API mode is 6× standard price.

Standard, short-context. Prompts over 272k input tokens are billed at 2× input and 1.5× output for the full request.

GPT-6 Sol

Existing API work built on GPT-6 Sol; new work should start on GPT-6.1 Sol.

  • The first GPT-6 Sol release, at the same API price as GPT-6.1 Sol.

Caveats

  • OpenAI's model page points to GPT-6.1 Sol as the newer Sol model.

GPT-6 Luna

Lots of short, cheap jobs — classification, drafts, and bulk API calls.

  • Cheapest current GPT-6 API model listed here ($0.10 / $0.50 per 1M).
  • Same 1.05M context window as Astra.
  • OpenAI’s pick for focused, high-volume tasks.

Caveats

  • Not in regular ChatGPT conversations, per OpenAI’s Work and Codex help article.
  • OpenAI positions it below Sol and Astra for hard work.

Standard, short-context. Prompts over 272k input tokens are billed at 2× input and 1.5× output for the full request.

GPT-5.5

Existing API integrations that are not ready to move to GPT-6.

  • Previous OpenAI flagship; still available on the API.
  • Same 1.05M context and 128k max output as the GPT-6 models.

Caveats

  • OpenAI now recommends GPT-6 Astra / Sol / Luna for new work.

Listed for prompts under 272k context length. Prompts over 272k are 2× input and 1.5× output.

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