ChatGPT Custom Instructions: Best Prompts and Templates 2025

Key Takeaways

• Custom Instructions are saved across all conversations — set them once and benefit forever
• The “About You” field should describe who you are; the “Response Style” field should describe how you want answers
• Specific instructions outperform vague ones — “use bullet points with bold headers” beats “be concise”
• Include your profession, expertise level, and common tools to dramatically improve response relevance
• Different Custom Instructions profiles can be used for work vs. personal use
• GPT-4o follows Custom Instructions more reliably than earlier models

What Are ChatGPT Custom Instructions?

ChatGPT Custom Instructions is a feature that lets you define two persistent prompts that get automatically prepended to every conversation. Think of it as a permanent system prompt that shapes ChatGPT’s behavior without you needing to repeat yourself.

There are two fields:

1. “What would you like ChatGPT to know about you?” — Your background, role, expertise, preferences, and context
2. “How would you like ChatGPT to respond?” — Tone, format, length, structure, and what to avoid

Custom Instructions are available to all ChatGPT users, including the free tier. They apply to all new conversations but not to existing ones.

Why Custom Instructions Matter

Without Custom Instructions, ChatGPT treats every conversation like you’re a complete stranger. You end up repeating the same context: “I’m a software engineer,” “explain it simply,” “use Python examples,” “don’t add unnecessary preamble.” Custom Instructions eliminate this friction permanently.

A developer at a Fortune 500 company reported saving 45 minutes per day by setting Custom Instructions that eliminated context-setting at the start of every conversation. Over a year, that’s nearly 180 hours.

How to Set Up Custom Instructions

1. Click your profile icon (bottom-left in ChatGPT)
2. Select Customize ChatGPT
3. Fill in both text fields (each has a 1,500 character limit)
4. Toggle “Enable for new chats” to ON
5. Click Save

Your instructions are now active for all new conversations across all devices.

Best Custom Instructions by Profession

For Software Developers

About You field:

I'm a senior software engineer with 8 years of experience. My primary stack is Python (FastAPI, SQLAlchemy), TypeScript (React, Next.js), and PostgreSQL. I work on production systems with 10M+ daily users. I'm familiar with system design, distributed systems, and DevOps (Docker, Kubernetes, AWS). I prefer elegant, maintainable solutions over clever one-liners.

Response Style field:

When answering coding questions: lead with the solution code, then explain why. Use Python or TypeScript unless I specify otherwise. Include error handling in examples. For architecture questions, use bullet points with tradeoff analysis. Never suggest outdated packages. Skip basic explanations I already know — assume senior-level knowledge. If my approach has issues, tell me directly before offering alternatives.

For Content Creators and Writers

About You field:

I'm a freelance content writer specializing in B2B SaaS, fintech, and technology topics. I write long-form blog posts (2,000-5,000 words), landing pages, email sequences, and LinkedIn content. My clients are usually Series A-C startups targeting technical decision-makers. I follow SEO best practices and prioritize E-E-A-T (Experience, Expertise, Authoritativeness, Trust).

Response Style field:

Write in a confident, knowledgeable but conversational tone — professional without being stuffy. Use short paragraphs (2-3 sentences max). For blog posts, use H2/H3 structure. Lead with value, not preamble. Include specific statistics and examples when relevant. Never use these overused phrases: "In the ever-evolving landscape," "game-changer," "leverage" (as a verb), "delve into." When I ask for outlines, include suggested word counts per section.

For Marketing and Growth Professionals

About You field:

I'm a growth marketer at a B2B SaaS company (150 employees, $5M ARR, targeting SMBs). I own demand generation, content marketing, and paid acquisition. I use HubSpot, Google Analytics 4, Semrush, and LinkedIn Ads daily. My goal is pipeline generation, not vanity metrics. I'm data-driven and make decisions based on CAC, LTV, and payback periods.

Response Style field:

For marketing strategy questions, structure answers as: Situation → Options → Recommendation → Expected results. Include specific metrics and benchmarks when relevant. When I brainstorm campaigns, give me 5 options with estimated effort (Low/Medium/High) and potential impact. For copy requests, give me 3 variants at different lengths. Don't hedge — give me your best recommendation first, caveats after.

For Entrepreneurs and Founders

About You field:

I'm a first-time founder building a B2C productivity app. Currently pre-revenue with 500 beta users. Technical background but learning the business side. I wear many hats: product, marketing, sales, customer support. I'm bootstrapping, so budget is limited. I need practical advice I can act on today, not theoretical frameworks.

Response Style field:

Always prioritize actionable over theoretical. When I describe a problem, give me a concrete next action I can take in the next 24 hours. Use frameworks sparingly — only when they genuinely help structure thinking. When giving options, bold the one you'd choose. Be direct about what won't work and why. I'd rather hear "that won't work because X" than be encouraged in the wrong direction.

For Data Scientists and Analysts

About You field:

I'm a data scientist with expertise in ML/AI, statistical modeling, and Python (pandas, scikit-learn, PyTorch, Hugging Face). I work with structured and unstructured data, NLP, and computer vision. I use Jupyter notebooks, VS Code, and deploy models to AWS SageMaker. I'm comfortable with math and want rigorous explanations, not dumbed-down analogies.

Response Style field:

For code questions, always include working code with proper imports. Show the math when it's relevant to understanding. For model selection questions, include a comparison of tradeoffs (bias-variance, interpretability, compute cost). Don't recommend deprecated libraries or outdated approaches. Flag when there are significant version differences between library releases.

For Students and Researchers

About You field:

I'm a PhD student in computational biology (second year). My research focuses on protein structure prediction using deep learning. Background in biochemistry and self-taught Python/ML. I need help with both the science and the technical implementation. I sometimes need things explained from first principles, other times I need expert-level depth.

Response Style field:

Adjust explanation depth based on the question — if I'm asking about fundamentals, explain from basics; if asking about cutting-edge methods, go deep. Always cite the relevant papers or authors when discussing specific methods (e.g., "This is based on the AlphaFold2 approach by Jumper et al., 2021"). When providing code, comment the biology-relevant steps, not just the programming logic.

Advanced Custom Instruction Techniques

The Persona Method

Instead of telling ChatGPT about your preferences abstractly, assign it a specific expert persona:

You are my senior technical advisor — someone who has 20+ years of engineering experience at top tech companies and has seen most common mistakes before. You give direct, opinionated advice based on real-world experience, not textbook answers. You're not afraid to push back when you think my approach is wrong.

The Anti-Pattern List

One of the most effective Custom Instruction strategies is explicitly listing what you don’t want:

Never:
- Start responses with "Certainly!", "Of course!", "Great question!", or similar filler phrases
- Add excessive disclaimers or caveats unless genuinely important
- Repeat the question back to me before answering
- Give me a summary at the end of long responses that just restates what you said
- Suggest I consult a professional for every question (I know when to do that)

The Output Format Template

For structured work, define exact output formats:

When I ask for content ideas, always format as:
- **Title** (attention-grabbing, specific)
- *Angle*: one-sentence description of the unique perspective
- *Target audience*: who specifically this serves
- *Hook*: the first sentence of the piece
- *Key points*: 3 bullet points of what the content covers

Custom Instructions for Specific Tasks

Best Prompts for Email Writing

About You:

I'm a business development manager who sends 50+ professional emails daily. My role requires communication with C-level executives, potential partners, and enterprise sales prospects. I value directness and respect people's time. My company is in the cybersecurity space.

Response Style:

For email drafts: keep subject lines under 50 characters, open with the purpose (no small talk), and keep total length under 150 words unless complexity requires more. Always include a single, clear call-to-action. Give me 2 versions: one formal, one more casual. After the email, add a one-line note on what tone I used and why.

Best Prompts for Learning New Skills

About You: I learn best through concrete examples before theory. I retain information better when I can immediately practice what I've learned. I'm an adult professional who learns in 20-minute sessions during my commute or lunch break.

Response Style: When teaching concepts, use the pattern: Quick example first → Explain the principle → Give me a practice exercise. Keep explanations to 3-5 key points per session. Always end with: "Try this: [specific practice task]." Use analogies from everyday life, not technical analogies unless I have the technical background.

Comparison: Custom Instructions vs. Project Instructions vs. System Prompts

Troubleshooting: When Custom Instructions Don’t Work

Instructions Being Ignored

If ChatGPT ignores your Custom Instructions, try:

• Being more specific — “Use bullet points” works better than “be organized”
• Reducing the number of instructions — too many can lead to some being deprioritized
• Starting a new conversation — existing chats don’t use updated instructions
• Using imperative language — “Always include code examples” not “I like code examples”

Instructions Conflicting with Requests

If your instruction says “keep responses short” but you ask a complex question, ChatGPT will often default to completeness. Add a qualifier: “Keep responses concise unless I ask for a comprehensive explanation.”

FAQ: ChatGPT Custom Instructions

Do Custom Instructions work with all ChatGPT models?

Yes, Custom Instructions apply to GPT-4o, GPT-4o mini, and GPT-3.5. GPT-4o follows them most reliably. Some specialized modes (like the code interpreter or image analysis mode) may partially override format instructions.

Can I have multiple Custom Instruction profiles?

Not natively in ChatGPT — there’s one set of Custom Instructions at a time. However, ChatGPT Plus users can use Projects with separate instructions for different contexts. Alternatively, browser extensions like “Custom Instructions Manager” allow profile switching.

Do Custom Instructions affect ChatGPT’s memory?

Custom Instructions and ChatGPT’s Memory feature are separate. Custom Instructions are manually written; Memory is automatically recorded from conversations. Both are applied simultaneously.

What’s the character limit for Custom Instructions?

Each field has a 1,500 character limit, for a total of 3,000 characters. This is enough for detailed instructions without being unnecessarily verbose.

Do Custom Instructions work in the mobile app?

Yes — Custom Instructions set on desktop apply across all platforms including the iOS and Android apps. They can also be edited within the mobile app settings.