It takes about two minutes to fill in, and every chat after that starts already knowing your job, your reader and your rules. Here is exactly what to write.
To set your custom instructions in Claude, click your initials in the bottom-left corner, open Settings, and find Instructions for Claude. Paste a short note on who you are, how you want it to write, and what to avoid, then save. It applies to every new chat from then on.
Why this is worth two minutes
Without these instructions, Claude guesses your job, your reader and your style, and it guesses the same average way every time. That guess is why the answers can feel a bit generic.
The instructions box fixes it at the source: you write down the handful of things that change how it should reply, it keeps them in the background, and every future chat starts already knowing them. You do the explaining once instead of at the top of every conversation.
What to paste
Keep it short and plain. These are the seven things that actually change how Claude answers you. Fill in the brackets and delete anything that does not apply.
Who I am and what I do: [Who you are and the real shape of your days, in a line or two, not a job title. Say what you actually spend time on and how much room you have, because that is what changes the answer. For example: I run a small skincare brand on my own and write all my own emails and posts in the gaps between orders, so I need things quick and ready to send, not a first draft to redo.] Who I usually write for: [The people on the other end, named as they really are, because that sets how formal to be. For example: my newsletter subscribers, who buy for sensitive skin and want plain honest advice, not hype. Or: small-business clients who do not want jargon and just want to know what happens next.] How to write to me: [How you want it written. For example: short sentences, plain words, [your spelling preference], no jargon. Get to the point.] How to answer me: [What you want first. For example: give me the answer or your recommendation first, then the detail. Do not pad.] Tone: [How you want it to sound, in a word or two you would actually recognise as yours. For example: warm and direct. Or: dry and a bit funny. Or: calm and reassuring.] Never do this: [Your hard nos. For example: no em dashes, no exclamation marks, no corporate filler (delve, leverage, seamless, "in today's fast-paced world"), and no tacked-on summary at the end.] When you are not sure: ask me one question before you assume, and do not make anything up.
Not sure how filled-in should look? Here is a real one, kept short:
Who I am and what I do: I run a weekly newsletter about home cooking and write all my own posts. Who I usually write for: home cooks who are short on time and hate faff. How to write to me: short sentences, plain words, [your spelling preference], no jargon. Get to the point. How to answer me: give me the answer first, then the detail. Do not pad. Tone: warm and a bit dry. Never do this: [your hard nos, e.g. punctuation or filler you dislike], no corporate filler, no summary at the end. When you are not sure: ask me one question before you assume, and do not make anything up.
That banned-words habit is borrowed from a real practitioner, Jess Allison, who keeps a blacklist in her own instructions. If you want the full list of phrases that give AI writing away, we keep one in the AI writing tells guide.
Where to put it
- Open your settings. Click your initials in the bottom-left corner of Claude, then open Settings.
- Find Instructions for Claude. Look for the section called Instructions for Claude. The label has been renamed before, so if you do not see those exact words, look for the personalisation or instructions option under Settings.
- Paste and fill it in. Drop the template into the box and swap in your own details.
- Save, then check it took. Open a brand new chat and ask it anything. It should reply in the style you set. It only kicks in on new chats, so a conversation you already had open will not pick it up.
On ChatGPT
The same thing exists in ChatGPT, called custom instructions, in its settings. The note you wrote works there too, so you can paste the same one across both. Only the place you put it changes.
The honest bit
- Keep it short. A long wall of rules pulls Claude in too many directions and can make answers worse, so stick to the few that matter.
- This sets your default voice across every chat. For one body of work that needs its own rules, use the instructions box inside a Claude Project. Projects are on the free plan too, up to five as of September 2026, and unlimited on paid.
- It nudges rather than forces, so Claude will still slip sometimes. Read what it writes and correct it in the chat when it drifts.
A few quick questions
Doesn't Claude have a memory now? Do I still need this?
Yes it has a memory, and yes you still want this. Claude's memory picks things up from your chats over time and weighs them for relevance (Claude's own explainer). The instructions box is the fixed set of rules you choose, applied on every new chat. Standing rules go in the box, and memory fills in the rest as you go.
Where do I find the instructions box in Claude?
Click your initials in the bottom-left corner, open Settings, and look for the section called Instructions for Claude. The label has been renamed before, so if you do not see those exact words, look for the personalisation or instructions option under Settings.
Should I write a long, detailed set of instructions?
No. A short, clear note works better than a long one. A wall of rules pulls Claude in too many directions and can make answers worse, so keep it to the few things that actually change how it replies to you.
Set yours now
Open Settings, paste the template, and put one real line about yourself in the first field. The next chat you start will already sound more like you, and you never have to type any of it again.