How to Build Your First Custom GPT

A custom GPT is a saved version of ChatGPT with its own instructions, knowledge files, and behavior, so you stop pasting the same long prompt every time. This guide builds a simple one from scratch using the GPT Builder, then saves it so it shows up in your sidebar for instant reuse.

What you need

• A ChatGPT Plus, Pro, Team, or Enterprise plan (custom GPTs are not available on the free tier)
• A clear idea of one repetitive task you want to automate
• About 10 minutes

Step 1: Open the GPT editor

In the left sidebar click GPTs, then the Create button in the top right. You land in a two-pane editor: the Create tab on the left where you chat with the builder, and a live Preview on the right.

Step 2: Describe the GPT in plain English

In the Create chat, describe what the GPT should do in one or two sentences. The builder will draft a name, a profile picture, and a first set of instructions, then ask follow-up questions to refine them. Answer them like you would brief a coworker.

Step 3: Switch to Configure and tighten the instructions

Click the Configure tab to see every field directly: Name, Description, Instructions, Conversation starters, Knowledge, and Capabilities. The Instructions box is the heart of the GPT. Replace any vague generated text with specific rules.

You rewrite rough emails into clear, friendly, professional English.

Rules:
- Preserve the original meaning. Never invent facts, names, dates, or numbers.
- Keep it concise: cut filler, keep the core message.
- If a detail seems missing (a deadline, a link), ask one short question
  instead of guessing.
- Output only the rewritten email unless asked for an explanation.

Step 4: Add conversation starters and save

Add two or three conversation starters so the GPT is usable in one click, for example Polish this draft or Make this shorter. When you are happy, click Create in the top right, choose who can access it (Only me is the safe default), and confirm. It now appears under GPTs in your sidebar.

Result

You now have an Email Polisher GPT pinned in your sidebar. Open it, paste a messy draft, and it returns a clean version that follows your rules every time, with no setup prompt to re-type.