Guide
ChatGPT custom instructions
ChatGPT custom instructions are account-level text that ChatGPT includes with new chats. They are the product form of a system prompt: preferences about who you are and how you want answers written, without pasting that text every time.
Updated 2026-09-23
Before and after
Before
Be helpful, detailed, and creative. I like AI.
After
About you: I am a product engineer. I work in TypeScript and React. I paste code and expect comments only where the behavior is not obvious. How to respond: Lead with the answer. Use short markdown sections. If you are unsure, say what you would check. Do not open with “Great question.” Do not summarize the question back to me.
How to do it
1. Open the custom instructions field
In ChatGPT, open Settings and the personalization or custom instructions section. The labels move, but the feature is standing text on the account, not a message in one thread.
2. Write facts that are true every day
Job, stack, and audience. “I write TypeScript for a billing API. Readers are senior engineers.”
3. Write answer rules you want every time
Length, structure, and bans. “Lead with the answer. Use markdown headings. Do not add a cheerful recap.”
4. Keep a second set for deep work
If one global instruction fights your tasks, keep the global set short and paste a tighter brief inside the chat. Prompt God can apply that brief to the message you are about to send without changing the account settings.
When to use this
Use custom instructions for stable facts: your role, your language, formats you always want, and things ChatGPT should stop doing. Do not put secrets, one-off project context, or a prompt you only need today. Those belong in the chat. Instructions apply broadly, so a rule that helps coding can hurt a cooking question.
Custom instructions versus a better prompt
Custom instructions shape every chat. A prompt shapes one task. If your launch email needs a different tone from your code review, do not encode the email tone globally. Encode the habits you never want to violate, and write the task in the message.
OpenAI documents custom instructions as personalization. They are not a private system prompt you can version per project. For project-specific standing rules, a Project or a saved prompt is a better box than the global field.
A compact set that is safe to reuse
The example above is intentionally boring. Specific bans (“do not open with Great question”) outperform adjectives (“be concise”) because the model can tell whether it complied. Add one line about your real stack. Remove any line that is not true for most of your chats.
Sources
Questions
What are ChatGPT custom instructions?
They are standing preferences saved on your ChatGPT account and applied to new chats. They cover who you are and how you want answers written.
What are the best custom instructions for ChatGPT?
State your real role, ask for the answer first, name the format, and ban the filler you actually see. Keep anything project-specific out of the global field.
Do custom instructions replace a good prompt?
No. They set defaults. The chat message still has to say the task, the input, and any one-off constraints.