What changed in GPT-5.6 Sol in ChatGPT?

OpenAI retuned GPT-5.6 Sol for everyday chat: more direct answers, tighter formatting, less unnecessary detail, and stronger reliability on dates, numbers, rules, sources, and assumptions. OpenAI reports 68% fewer factual errors than GPT-5.5-Instant on finance, medical, and legal evaluations.

How does the new reasoning slider work?

The reasoning slider lets Plus and Pro subscribers pick how much thought GPT-5.6 Sol puts into each answer. Keep it low for quick questions and raise it for research, coding, or planning. The slider ships on web, mobile, and desktop and replaces the old split between Instant and Thinking.

What do Free users get?

Free and Go users move to GPT-5.6 Luna as the default and get unlimited text chats. A new Think button on ChatGPT triggers deeper reasoning for harder questions. Separate limits still apply for files, images, voice, and image generation. OpenAI reports 62% fewer factual errors on Luna versus the model it replaces.

Does this change GPT-5.6 Sol in Codex or ChatGPT Work?

No. The improvements target GPT-5.6 Sol as used inside ChatGPT for chat. GPT-5.6 Sol in Codex and in ChatGPT Work is not affected by this update, so coding and enterprise agent behavior stays where it was.

How do I get the new Sol and the slider?

The upgraded GPT-5.6 Sol and the reasoning slider are rolling out immediately to ChatGPT Plus and Pro subscribers across web, mobile, and desktop. Free and Go users receive the Luna default and unlimited text chats over the following week as the rollout expands.

OpenAI · 2026-08-06 · major

ChatGPT ships smarter GPT-5.6 Sol — new reasoning slider, unlimited free chats

OpenAI retuned GPT-5.6 Sol in ChatGPT for more direct answers with 68% fewer factual errors than GPT-5.5-Instant, added a slider that controls reasoning depth for Plus and Pro, and gave Free users unlimited text chats on GPT-5.6 Luna.

OpenAI announcement art for the improved GPT-5.6 Sol update in ChatGPT

OpenAI retuned GPT-5.6 Sol in ChatGPT, added a reasoning slider, and made text chats unlimited for Free users.

Key specs

Factual errors vs gpt 5.5 instant	68% fewer
Free tier text chats	unlimited
Free tier default model	GPT-5.6 Luna
Chat gpt weekly users	1 billion

Quick facts

Maker	OpenAI
Updated model	GPT-5.6 Sol (in ChatGPT)
New free-tier default	GPT-5.6 Luna, unlimited text chats
New control	Reasoning slider on web, mobile, desktop
Unified experience	Instant and Thinking merged into one
Availability	Plus and Pro now; Free and Go rolling out this week
Not changed	GPT-5.6 Sol in Codex and ChatGPT Work

What is it?

ChatGPT's default paid model, GPT-5.6 Sol, now gives more direct answers with tighter formatting and 68% fewer factual errors on finance, medical, and legal checks than GPT-5.5-Instant. Plus and Pro subscribers also gain a slider that controls how much thinking Sol puts into each answer, and Free users move to GPT-5.6 Luna with unlimited text chats.

How does it work?

OpenAI merged ChatGPT's Instant and Thinking modes into one experience powered by GPT-5.6 Sol, then exposed the old choice as a slider on web, mobile, and desktop. Free and Go users get GPT-5.6 Luna as the default, a new Think button for deeper reasoning on hard questions, and no cap on text chats. GPT-5.6 Sol inside Codex and ChatGPT Work is untouched by this update.

Why does it matter?

The retuned Sol answers everyday questions with fewer hedge words and fewer bad facts, which is the exact complaint most ChatGPT users bring up. The reasoning slider lets paid users trade latency for depth without switching models, and unlimited free chats on Luna land as OpenAI passes 1 billion weekly ChatGPT users.

Who is it for?

ChatGPT users across Free, Plus and Pro plans

Frequently asked questions

What changed in GPT-5.6 Sol in ChatGPT?: OpenAI retuned GPT-5.6 Sol for everyday chat: more direct answers, tighter formatting, less unnecessary detail, and stronger reliability on dates, numbers, rules, sources, and assumptions. OpenAI reports 68% fewer factual errors than GPT-5.5-Instant on finance, medical, and legal evaluations.
How does the new reasoning slider work?: The reasoning slider lets Plus and Pro subscribers pick how much thought GPT-5.6 Sol puts into each answer. Keep it low for quick questions and raise it for research, coding, or planning. The slider ships on web, mobile, and desktop and replaces the old split between Instant and Thinking.
What do Free users get?: Free and Go users move to GPT-5.6 Luna as the default and get unlimited text chats. A new Think button on ChatGPT triggers deeper reasoning for harder questions. Separate limits still apply for files, images, voice, and image generation. OpenAI reports 62% fewer factual errors on Luna versus the model it replaces.
Does this change GPT-5.6 Sol in Codex or ChatGPT Work?: No. The improvements target GPT-5.6 Sol as used inside ChatGPT for chat. GPT-5.6 Sol in Codex and in ChatGPT Work is not affected by this update, so coding and enterprise agent behavior stays where it was.
How do I get the new Sol and the slider?: The upgraded GPT-5.6 Sol and the reasoning slider are rolling out immediately to ChatGPT Plus and Pro subscribers across web, mobile, and desktop. Free and Go users receive the Luna default and unlimited text chats over the following week as the rollout expands.

Try it

https://chatgpt.com