Custom Instructions let you tell ChatGPT once about your role, preferences, writing style, and answer format. After that, new chats can use that context automatically instead of making you repeat it every time.
Does this affect you?
Use this for ChatGPT on the web, iOS, Android, Windows, or Mac. Custom Instructions are available on free and paid plans.
Turn on and set up Custom Instructions
The setting takes about a minute to configure.
- On web or desktop, click your name or profile icon and open Custom instructions, or look under Settings > Personalization.
- On mobile, open Settings and look under Account or Personalization for Custom Instructions.
- Turn on Enable for new chats if a toggle appears.
- Fill in the box about you with role, background, interests, and expertise level.
- Fill in the response preference box with tone, format, length, and things to avoid.
- Keep it focused because the total space is limited.
- Click Save.
Instructions apply to new conversations after saving. Existing chats may keep their original context.
What to actually write
Concrete instructions work better than personality labels.
- About you: Include your role and relevant background, such as high school biology teacher, beginner programmer, small business owner, or nontechnical manager.
- How to respond: Specify length, format, tone, and detail level. For example, keep answers under 200 words unless I ask for more detail.
- Things to avoid: Add repeated annoyances, such as avoiding certain words, excessive disclaimers, or ending every answer with a follow-up question.
- Do not include temporary context: Today’s project, a current date, or short-term preference belongs in the chat, not in instructions that apply indefinitely.
- Revise occasionally: If ChatGPT repeatedly does something unhelpful, add or tighten a line in the instructions.
More control
Instructions follow your account
Once saved, Custom Instructions apply across the web, phone, and desktop app where you are signed into the same account.
Do not store sensitive details there
Custom Instructions are account data and may be covered by the same model improvement settings as regular chats, depending on your account. Review Settings > Data Controls and avoid private information you would not want stored.
Test in a fresh chat
Start a new conversation after editing instructions. If the result still misses, the instructions may be too vague or contradictory, such as asking for both very brief and detailed explanations.
Sources
- OpenAI Help Center – ChatGPT Custom Instructions (2026)
- OpenAI – Custom instructions for ChatGPT (2025)
- OpenAI Help Center – Key Guidelines for Writing Instructions for Custom GPTs (2026)