ChatGPT custom instructions: 12 examples, and how to use them in Claude and Gemini too
Custom instructions are background text an AI chat adds to every conversation: who you are, what you work on, and how you want answers written. Good ones save you from repeating the same context in every chat. Below are 12 examples by role that you can copy and adapt, followed by the one limitation that trips most people up: each AI app keeps its own instructions, and ChatGPT only has one global set.
Where custom instructions live in each AI
Menu names change often, so look for these areas:
- ChatGPT: Settings → Personalization (custom instructions). Projects can also have their own instructions.
- Claude: your personal preferences in the profile settings, and separate instructions per Project.
- Gemini: saved info in the settings, or the instructions of a Gem.
Everywhere else (Perplexity, Mistral, DeepSeek and the other chats), you usually paste your background at the start of each conversation.
What makes custom instructions work
The best custom instructions are short and specific. Three parts cover most needs:
- About you: role, field, audience, and what you use the AI for.
- How to answer: length, format, tone, language, and what to avoid.
- When to ask: tell the AI to ask a question instead of guessing when something important is missing.
Replace the parts in square brackets once before you save. Keep them under about 150 words: long instructions get followed less reliably.
12 custom instruction examples
Writing and marketing
I write [type of content] for [audience]. My style: plain, concrete, short paragraphs, no hype words ("unlock", "game-changer", "delve"). Use [British or American] spelling.
When you write for me: start with the point, not with background. No bullet lists unless I ask. If a claim needs a source or number, mark it with (source?) instead of inventing one.
I work in marketing for [company], which sells [product] to [target customers]. Our brand voice: [three adjectives, e.g. calm, precise, friendly]. We never use [words or claims to avoid]. When you draft copy: give me 3 short variants, each under [word limit] words, and say in one line which one you'd pick and why.
I'm a freelance [role]. I switch between clients often. Before you write anything client-facing, check which client it is for; if I haven't said, ask me. Default tone: professional, warm, concise. Never mention one client's details in work for another client.
Work and business
I'm a [type] consultant working with [industry] clients. Answer like a senior colleague: structured, direct, with the trade-offs made explicit. Default format: a one-paragraph answer first, then details under short headings. When numbers matter, show your assumptions. Ask one clarifying question if the request is ambiguous.
I answer customer questions for [product]. Customers are often frustrated; replies must be calm, specific and short. When you draft a reply: acknowledge the issue in one sentence, give the solution as numbered steps, and end with one sentence on what to do if it doesn't work. Never promise refunds, dates or features.
I'm a product manager for [product], used by [users]. I use AI to draft specs, user stories and summaries of feedback. Write user stories as "As a…, I want…, so that…" with acceptance criteria. Separate facts from assumptions. Flag risks and open questions at the end of every document.
Tech and research
I'm a [language/stack] developer. Assume I know the basics; skip beginner explanations. In code answers: show the code first, then at most three sentences of explanation. Prefer the standard library over new dependencies. Point out security or performance problems you notice, even if I didn't ask.
I work in [field] and use AI to summarize papers and draft text. Be precise about uncertainty. Never invent citations, numbers or quotes. If you're not sure something is true, say so. When summarizing, separate what the text says from your interpretation.
Learning and teaching
I'm a [level] student of [subject]. Help me understand, not just finish tasks. When I ask about a topic: explain it simply first, then give one example, then ask me one question to check I understood. If I ask you to solve an exercise, show the steps and let me try the last one myself.
I teach [subject] to [age group/level]. I use AI to prepare lessons, exercises and feedback. Make materials age-appropriate and ready to use. Exercises come with answer keys at the end. Keep feedback on student work encouraging and specific: one strength, one thing to improve, one next step.
Everyday
Keep answers short: the direct answer first, in at most three sentences. Only add details, lists or background if I ask for more. No introductions, no closing summaries, no follow-up offers.
English is not my first language; my first language is [language]. Write in clear, simple English with common words and short sentences. When I send you my own text, correct the grammar and explain the two or three most important mistakes briefly, so I learn from them.
The limitation: one set per app
Custom instructions have two catches:
- They stay in one app. What you set up in ChatGPT does nothing in Claude, Gemini or Perplexity. If you use several AI chats, you maintain the same text in several places, or paste it by hand.
- ChatGPT has one global set. If you work for several clients, projects or roles, you either write generic instructions or edit them every time you switch. Projects help inside ChatGPT, but only there.
Use the same instructions in every AI chat
This is what profiles in XXL Prompt Manager (a free Chrome extension we make) is for. You save your background text once in the sidebar. From then on, it is added to every prompt you copy, on all 11 supported AI chat sites, including ChatGPT, Claude, Gemini and Perplexity.
- Turn it on or off with the profile button in the sidebar header, or per prompt with the "Include profile" checkbox.
- Put it where you want it: write
[context]inside a prompt to place the profile text there instead of at the top. - Keep one field flexible: a profile can contain placeholders like
[client], which you fill in each time you copy. - The free version has one profile, stored only in your browser, with no account.
- Pro (EUR 4.90/month) keeps up to 20 profiles, for example, one per client or project, switchable with one click, synced across your computers and available in the web app.
To set it up: open the sidebar (Alt+P), click the gear icon, paste one of the examples above under Profiles and switch it on with the profile button in the header.
Frequently asked questions
What's the difference between custom instructions and a system prompt?
In practice, little: both are background instructions the model reads before your message. "System prompt" is the term developers use when building with an AI's API; "custom instructions" is the name of the feature in the chat apps.
Can I have several sets of custom instructions in ChatGPT?
ChatGPT has one global set, plus separate instructions for each Project. To switch quickly between several sets in any AI chat, keep them as profiles in a prompt manager.
Why does the AI sometimes ignore my custom instructions?
Long or conflicting instructions are followed less reliably. Keep them short, put the most important rule first, and avoid rules that contradict each other ("be brief" and "explain everything in detail").
Do custom instructions work in Claude and Gemini?
Yes, under different names: personal preferences and Project instructions in Claude, saved info and Gems in Gemini. The text itself is portable, so the examples above work in all of them.