Treat GPT‑5.6 Sol as the same model in ChatGPT and adjust its reasoning investment by task: use a faster setting for simple questions, then increase the reasoning setting for planning, research, writing, coding, and decision-making.
Suitable tasks: client-side routing for factual questions, web searches, planning, research, writing, coding, and multi-step decision-making.
Unsuitable tasks: scenarios that require precise API control of reasoning.effort or a custom service tier; this page describes only the ChatGPT product slider.
Applicable model version: the updated GPT‑5.6 Sol in ChatGPT; the default model for Free and Go users is GPT‑5.6 Luna.
Applicable client, Agent, or API: ChatGPT on the web, mobile, and desktop; the page does not disclose a corresponding API field.
Recommended reasoning setting and parameters: choose the faster setting for everyday questions; choose a higher reasoning setting for multi-step planning, research, writing, coding, or decision-making; exact setting names depend on the client.
The following is a client configuration card organized from the official routing guidance, not API request syntax:
Task routing:
1. If the question is a simple fact, short rewrite, or minor edit, start with GPT‑5.6 Sol's faster reasoning setting.
2. If the task requires multi-step planning, research, writing, coding, or a high-value decision, increase the reasoning setting before submitting.
3. If the answer depends on dates, numbers, sources, rules, or assumptions, ask the model to verify the basis first and then provide a conclusion.
4. If key facts remain uncertain, do not rely on simply increasing the reasoning setting; add sources or perform a human review.
5. For Free/Go accounts, use Luna for routine text tasks; use Luna's “Thinking” button for harder problems.Run the same question separately at a faster and a higher reasoning setting.
Compare factual errors, omissions, answer length, and completion time rather than looking only at writing style.
For planning, research, writing, and coding tasks, keep a fixed acceptance criterion, then decide whether to increase the setting.
Record the client, date, model setting, and whether tools were used; the page explicitly states that the updated chat Sol is not the same as the Sol version that supports Codex.
OpenAI describes the updated Sol as more focused, adjusting detail to the question, reducing unhelpful formatting, and correcting unhelpful agreement.
In internal evaluations using financial, medical, and legal prompts, the proportion of answers with at least one factual error fell by about 68% relative to GPT‑5.5 Instant.
Plus/Pro users can switch between instant answers and more in-depth thinking with the slider; the page does not disclose evaluation samples, per-question inputs, or external reproduction experiments.
Free users switch to Luna and can use the “Thinking” button for harder questions; file uploads, images, and other tools remain limited.
The 68% figure is a relative change from OpenAI's internal evaluation, not a publicly reproducible accuracy rate.
The page says this update applies only to the ChatGPT chat experience; it should not be used to infer that Codex or API model behavior is exactly the same.
Increasing the reasoning setting takes more time or consumption and does not necessarily deliver an equivalent quality gain; record A/B results on representative tasks.
The official announcement summarizes the update as “more focused answers” and explicitly places instant answers and more in-depth thinking within the same Sol experience.
GPT-5.6 Sol