# How do I make ChatGPT write in my voice?

For free, put a concrete style note in custom instructions and keep a Project that holds a few real samples of your writing with its own instructions; memory and the base style setting help with tone but do not copy your voice. If you want every draft rewritten from your own samples, fitted to where it is going and learning from what you send, add Ownhand as a developer mode app, which OpenAI offers on Plus, Pro and work plans on the web.

By Jordan Gibbs, founder of Ownhand at Thalient Labs. Updated 2 October 2026.

ChatGPT has five settings that touch on style. Two do most of the work. One is good for standing rules. One barely affects drafts. One is being phased out. Below are the steps and limits for each, from OpenAI's own docs, and what Ownhand adds.

## The options at a glance

| Setting | Where | What it gives you | Catch |
| --- | --- | --- | --- |
| Custom instructions | Settings > Personalization | A standing note in every chat | 1,500 characters on Free and Go, 5,000 on paid plans |
| Base style and tone | Settings > Personalization | A personality such as Professional or Efficient | Drafts such as emails follow your instructions and context instead |
| Memory | Settings > Personalization > Memory | Preferences and details carried between chats | Facts about you, drawn from how you talk to ChatGPT |
| Projects | New project, in the sidebar | Samples as files or text, plus project instructions | Only applies inside that Project |
| Custom GPTs | Explore GPTs | A reusable assistant with its own instructions | No new GPTs on Free, Go, Plus or Pro; retirement planned |
| Ownhand | A developer mode app | Each draft rewritten from your Hand, for one of 12 occasions, learning from what you send | Plus, Pro and work plans on the web; $1 free, then about half a cent per rewrite |

## 1. Start with custom instructions

1. Open Settings, choose Personalization, and check that Enable customization is on.
2. Type your note in the Custom Instructions field. It applies to all chats right away, including existing ones.

Free and Go plans get 1,500 characters. Plus, Pro and work plans get 5,000. That leaves room for rules and one short sample. Skip adjectives like "friendly but sharp". Write things a reader could check. A note along these lines works:

```
Emails: under 120 words. Open with "Hi Sam," and nothing else. Sign off with my first name.
Slack: one or two sentences. Lowercase is fine. No bullet points.
Never open with a compliment or close by offering more help.
A reply I actually sent: [paste one]
```

Use a note when you mostly want shorter, plainer drafts. It does little for habits you can't name, and 1,500 characters fits only one short sample. For words worth banning, see [the phrases that make writing read as AI](https://ownhand.dev/answers/ai-writing-tells).

## 2. Do not count on the base style setting

Under Personalization, Base style and tone sets a personality, like Professional, Friendly, Candid, Quirky or Efficient. OpenAI's help article is direct about the limit. When you ask for an email draft or a social post, ChatGPT matches the tone to your instructions and the context. It may not use the personality you picked. Efficient is a good choice if you want short answers from ChatGPT itself. For drafts you send, your instructions and samples do the work.

## 3. Keep your samples in a Project

A Project keeps your chats, files, and instructions together. Inside it, project instructions override your global custom instructions. It's a free place to keep samples.

1. Select New project in the sidebar and name it, say "Writing as me".
2. Add 3 to 10 things you wrote and sent, as files or pasted text. Label each one with where it went: a Slack DM, an email to a client, an update to your manager.
3. Open the more options menu (•••), choose Project settings, and add instructions: "Write like my samples in this project. For each kind of message, match the length and opening of the samples of that kind."
4. Draft inside the Project. You can also drag an existing chat in, and it takes on the Project's instructions and files.

This works if you draft in one place, for a handful of message types, and you're happy to refresh the samples yourself. The limits: samples only help inside that Project, and nothing changes when you rewrite a draft before sending it.

Samples also have a ceiling. In an EMNLP 2025 paper, researchers gave leading models a few texts from each of more than 400 real people. The models matched style well on email and news. They fell short on blogs and forum posts.

## 4. Use memory for standing rules

With memory on, ChatGPT can draw on past chats, saved memories, custom instructions and, on some plans, files and connected apps. Tell it "remember that I sign emails with my first name only" and it will. You can review or correct what it holds under Settings > Personalization > Memory. Its picture of you comes from the way you type to ChatGPT. That's rarely how you write to a client.

## 5. What happened to custom GPTs

A "write as me" GPT used to be the standard answer. OpenAI's help center now says personal accounts (Free, Go, Plus and Pro) can't create new GPTs. It plans to retire custom GPTs in favor of plugins. Existing GPTs still work for now. Business, Enterprise and Edu workspaces can still create them where workspace settings allow. If you're starting fresh, put your samples in a Project.

## 6. Add Ownhand for drafts written from your samples

Ownhand is an MCP server. ChatGPT writes a draft, sends it with the occasion to the Ownhand write tool, and shows you the rewrite from your Hand. OpenAI's developer docs list developer mode for Plus, Pro, Business, Enterprise and Education accounts on the web. Free accounts can't add it.

1. In ChatGPT on the web, open Settings, then Security and login, and turn on **Developer mode**.
2. Go to ChatGPT Plugins, select the plus button, and create a developer mode app with the URL `https://ownhand.dev/mcp` and OAuth sign-in.
3. Sign in when asked, pick or create your Hand, and click Allow.
4. In a chat, choose Developer mode from the + menu and select Ownhand.
5. If you have no Hand yet, paste 5 to 10 things you wrote and ask ChatGPT to create one.

On Business plans, only admins and owners can turn on developer mode, so ask yours first. OpenAI flags developer mode as risky. A connected app can take actions in your tools. Ownhand's tools rewrite text, read your account, and update your Hand. None of them can send a message for you.

Then be explicit, as OpenAI's docs suggest for developer mode apps: "Use the Ownhand write tool to draft a cold email to the Acme CTO as me." Saying what the text is for picks the occasion. For a reply, paste the thread and say it's a reply. Ownhand matches how you write in that thread.

## What you get that a Project does not give you

Three things. Each draft fits one of 12 occasions, so a cold email and a DM to a teammate come out different. Each draft gets checked for AI tells and rewritten if it fails. After you send, ChatGPT reports what you actually sent. That's how your Hand improves. See [how Ownhand learns from what you send](https://ownhand.dev/answers/how-ownhand-learns-from-edits). The same follow-up, from two writers:

These examples are real output from the live API. Each AI draft was rewritten by a demo Hand: a fictional writer (an engineer, a founder, an ops lead, a designer or a consultant) built from a handful of samples.

**AI draft:** "Just following up on my previous message about the contract renewal. I understand you're busy, but it would be great to get your sign-off before the 15th."

**Demo Hand, engineer:** "need sign-off on the contract renewal before the 15th"

**AI draft:** "Just following up on my previous message about the contract renewal. I understand you're busy, but it would be great to get your sign-off before the 15th."

**Demo Hand, consultant:** "Following up on the contract renewal. Could you sign off before the 15th?"

Same deadline, same ask. The engineer drops the greeting and the line about being busy. The consultant keeps a polite question. With one style note in custom instructions, both would have received the same draft. A harder message, turning something down, from a designer:

**AI draft:** "Thank you for thinking of me for this opportunity. After careful consideration, I've decided to respectfully decline, as my current commitments would not allow me to give it the attention it deserves."

**Demo Hand, designer:** "I have to pass on this one. I'm too tied up right now to give it what it needs. Thanks for thinking of me."

It keeps the reason and the thanks, puts the decision first, and drops the formal phrasing the draft opened with.

## Which one to pick

- Free plan: custom instructions plus a Project with samples. Developer mode is not available to you.
- You want shorter, plainer answers from ChatGPT itself: the Efficient base style and a few rules in custom instructions.
- You draft one kind of message: a Project is enough.
- You send many kinds of messages and keep fixing drafts before they go out: Ownhand. New accounts get $1 of credit, and after that each rewrite costs about half a cent.

The same Hand works in Claude, Cursor and other MCP clients. For Claude, see [make Claude write like you](https://ownhand.dev/answers/make-claude-write-like-me). For style notes against samples in general, see [Ownhand or custom instructions](https://ownhand.dev/answers/ownhand-vs-custom-instructions).

## Follow-up questions

### Can I upload my writing samples to ChatGPT?

Yes. Add them to a Project as files or pasted text. ChatGPT uses them in that Project's chats. Label each one with where it was sent. Use only text you wrote yourself. Don't use samples an AI drafted, they teach it the wrong voice.

### How long can ChatGPT custom instructions be?

OpenAI's help center gives you 1,500 characters on Free and Go, and 5,000 on Plus, Pro, Business, Enterprise and Education. Spend them on rules a reader could check and one short sample. Keep the rest of your samples in a Project.

### Does Ownhand work on the free ChatGPT plan?

No. OpenAI's developer docs list developer mode for Plus, Pro, Business, Enterprise and Education accounts. On Free, use custom instructions and a Project. Or use Ownhand from another client like Claude, where a free account can add one custom connector.

### Will my samples be used to train models?

Ownhand doesn't train its own models on your writing. Its learning step runs on a model provider. That provider's terms let it use what Ownhand sends when you give feedback, and the privacy policy lists exactly what that is. On the ChatGPT side, OpenAI says content from custom instructions may be used to improve its models unless you opt out in its data controls.

### What happens to a writing-style GPT I already made?

It still works for now. OpenAI plans to retire custom GPTs and move those workflows to plugins, with a migration flow. Affected Enterprise workspaces have a planned retirement date of 11 December 2026. Other plans are expected to follow. Copy its instructions and samples into a Project so you have them either way.

## Sources

Checked on 2 October 2026. If something here is out of date, email [hi@thalientlabs.ai](mailto:hi@thalientlabs.ai) and we will fix it.

- [OpenAI Help Center: ChatGPT custom instructions](https://help.openai.com/en/articles/8096356-chatgpt-custom-instructions): Settings > Personalization, character limits per plan, use of instructions to improve models
- [OpenAI Help Center: Customizing your ChatGPT personality](https://help.openai.com/en/articles/11899719-customizing-your-chatgpt-personality): Base style and tone, and that email drafts follow your instructions and context
- [OpenAI Help Center: Memory in ChatGPT](https://help.openai.com/en/articles/8590148-memory-faq): what memory draws on, Settings > Personalization > Memory
- [OpenAI Help Center: Projects in ChatGPT](https://help.openai.com/en/articles/10169521-projects-in-chatgpt): files, pasted text, project instructions that override custom instructions
- [OpenAI Help Center: Creating and editing GPTs](https://help.openai.com/en/articles/8554397-creating-a-gpt): no new GPTs on personal accounts, planned retirement in favor of plugins
- [OpenAI Developers: ChatGPT developer mode](https://developers.openai.com/api/docs/guides/developer-mode): eligible plans, Settings > Security and login, creating an app for a remote MCP server
- [OpenAI Help Center: Developer mode and MCP apps in ChatGPT](https://help.openai.com/en/articles/12584461-developer-mode-and-mcp-apps-in-chatgpt): admin and owner rules on Business, Enterprise and Edu
- [Wang et al., Catch Me If You Can? Not Yet (EMNLP Findings, 2025)](https://aclanthology.org/2025.findings-emnlp.532.pdf): how well models imitate everyday authors from a few samples
- [Ownhand source code](https://github.com/jordan-gibbs/ownhand): occasions, the checker, reply matching and the learning loop

## Install

In Claude Code it is one line. You sign in through your browser, so there is no API key to copy.

```
claude mcp add --transport http --scope user ownhand https://ownhand.dev/mcp
```

For Claude, ChatGPT, Cursor, VS Code, Codex, Gemini CLI, Windsurf, Zed, Goose and Cline, see [Connect](https://ownhand.dev/connect). New accounts get $1 of free credit. After that you pay as you go, and each rewrite costs about half a cent.

More answers: [all questions](https://ownhand.dev/answers). Full reference: [Docs](https://ownhand.dev/docs).

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Page: https://ownhand.dev/answers/make-chatgpt-write-in-my-voice. Index for agents: https://ownhand.dev/llms.txt