Every time you start a new ChatGPT conversation, the AI begins from scratch — it doesn’t know your job, your preferred writing tone, or whether you want brief bullet points or detailed explanations. That costs you several back-and-forth messages just re-establishing context. Custom Instructions fix that.
Custom Instructions are a built-in feature available on both free and paid ChatGPT accounts that let you define two things once: background about yourself, and how you want ChatGPT to respond. Set them up in under three minutes, and every new conversation inherits those preferences automatically.
Quick Answer
Open ChatGPT, click your profile icon → Settings → Personalization → Custom Instructions. Fill in the first field with your role and context, and the second with your preferred response style. Toggle Enable for new chats to on, save, and every new conversation will use your preferences.
What Are Custom Instructions?
Custom Instructions are two persistent text fields stored with your OpenAI account:
- “What would you like ChatGPT to know about you?” — your profession, skill level, location, or ongoing projects.
- “How would you like ChatGPT to respond?” — tone (formal/casual), length (concise/detailed), format (bullets/prose), or any special preferences.
These act as a silent system prompt prepended to every new conversation. ChatGPT reads them before it reads anything you type, so you never have to repeat yourself across sessions.
Who Can Use Custom Instructions
Custom Instructions are available on free ChatGPT accounts and ChatGPT Plus. The one exception: they’re silenced in Temporary Chat mode, which is designed for private sessions with no saved context. If you rely on Custom Instructions, verify you’re not accidentally chatting in Temporary mode.
How to Set Up Custom Instructions
On Desktop (Browser)
- Go to chatgpt.com and sign in.
- Click your profile icon in the bottom-left corner.
- Select Settings.
- Click Personalization in the left sidebar.
- Click Custom Instructions.
- Fill in both text fields (see examples in the next section).
- Toggle Enable for new chats to on, then click Save.
Pro tip: Changes apply only to conversations started after you save — not to any chat already open. Open a fresh conversation tab immediately after saving to confirm the instructions are working.
On the ChatGPT Mobile App (iOS and Android)
- Tap the three horizontal lines in the top-left corner.
- Tap your profile name at the bottom of the menu.
- Tap Custom Instructions.
- Fill in both fields and tap Save.
What to Write in Each Field
Most users get stuck here. The key is specificity — vague instructions produce vague improvements. Here are tested examples across common use cases:
| Use Case | “Know About You” Field | “How to Respond” Field |
|---|---|---|
| Developer | Senior backend engineer, Python/Django, building B2B SaaS | Skip basic explanations, show code first, explain trade-offs briefly |
| Student | Undergrad biology student studying for exams | Use simple language, add analogies, end with a 2-sentence summary |
| Non-technical professional | Marketing manager, no coding background | Avoid jargon, keep responses under 200 words unless I ask for more |
| Writer | Freelance copywriter, B2B tech niche | Match professional tone, prefer active voice, flag weak word choices |
| Parent / Educator | Homeschooling parent, kids ages 8 and 11 | Explain as if to a curious 10-year-old, use real-world examples |
Troubleshooting tip: If your responses still feel generic after saving, confirm the Enable for new chats toggle is on and that you’ve opened a new conversation. Instructions won’t retroactively apply to a chat that was already open when you saved.
Common Mistakes to Avoid
- Writing too much. Each field holds up to 1,500 characters. Cramming in every detail causes ChatGPT to deprioritize what matters most. Stick to your 2–3 most important facts and 2–3 core response preferences.
- Contradicting yourself. Asking for “concise responses” in one field and “always include detailed examples with step-by-step breakdowns” in the other creates unpredictable output. Decide your priority and stay consistent.
- Never revisiting them. Your role, projects, and goals change. Stale instructions are almost as unhelpful as none — set a reminder to review every few months.
- Storing sensitive data. Don’t put passwords, financial details, or private health information in Custom Instructions. They’re stored on OpenAI’s servers and included in every single prompt you send.
- Forgetting Temporary Chat silences them. If a session opens in Temporary Chat mode, Custom Instructions are bypassed by design. Check the top of the chat window if you notice unexpectedly generic or impersonal responses.
To understand the full picture of what ChatGPT stores and how it builds a profile from your conversations, see our guide on what ChatGPT remembers and how to take back control.
Frequently Asked Questions
Do Custom Instructions work with GPT-4o and other models?
Yes. Custom Instructions apply regardless of which model you select — GPT-3.5, GPT-4o, or any other option. They feed in as a system prompt before your first message in every new chat.
Can people see my Custom Instructions if I share a chat link?
No. Shared conversation links display only the visible messages in that specific chat. Your Custom Instructions remain private and are never included in shared links.
How are Custom Instructions different from ChatGPT’s memory feature?
Custom Instructions are static text you write yourself — they don’t change unless you manually edit them. Memory is a separate feature that automatically saves facts ChatGPT picks up from your conversations. Both features can be active at the same time and complement each other.
Will Custom Instructions affect image generation (DALL-E) requests?
Partially. Style and tone preferences won’t change image output, but context about your role or purpose may influence how ChatGPT interprets ambiguous image prompts before sending them to the image model.
Can I have different Custom Instructions for different topics or projects?
Not natively — there’s one global set per account. ChatGPT Plus users can use Projects, which allow per-project instructions that override the global set within that workspace.
What happens if I delete my Custom Instructions?
ChatGPT reverts to its default behavior as if no instructions exist. Existing conversations are unaffected, and you can add new instructions again at any time.
Conclusion
Custom Instructions are one of the fastest setup-to-improvement ratios in any AI tool — a few minutes of configuration that pays off in every conversation from that point forward. Fill in both fields thoughtfully, save, and open a new chat to see the difference immediately.
For more ways to get sharper results, read our guide to 7 prompt techniques that make ChatGPT smarter. Still deciding which AI fits your workflow? Our ChatGPT vs Gemini vs Claude comparison breaks it down in plain terms.