A quick-start guide

Bring Your Voice From ChatGPT Into Claude

You've spent months teaching ChatGPT how you write, what you're working on, and the rules you care about. Here's how to carry all of that into Claude — so it knows you from the very first message, instead of starting from scratch.

⏱ About 30 minutes, start to finish

How is Claude different from ChatGPT?

They're close cousins — if you can use one, you can use the other. But a few things stand out once you make the move:

It sounds more human

Claude is known for natural, less "robotic" writing, and it's especially good at picking up and holding your voice. That's the whole reason the voice hand-off in this guide works so well.

It holds a lot more in its head

Claude can work with very long documents and long conversations without losing track of what you said earlier — handy when you paste in big reference material or think through something complex.

It builds things you can keep and edit

Alongside the chat, Claude can produce a document, table, or simple web page in a side panel you can revise and reuse — not just a wall of text to copy out.

It's careful with your rules

Claude tends to follow the specific do's and don'ts you give it, and it will tell you when it's unsure rather than confidently guessing.

Why use Projects in Claude?

A Project is a dedicated workspace inside Claude for one client, brand, or line of work. It's the single feature that makes the switch worth it — here's what it does for you:

It remembers you — permanently

Anything you put in a Project's instructions applies to every chat you start inside it. You set up your voice and context once, and Claude knows it from the first message — no re-pasting, no re-explaining every time you open a new chat.

Your work stays organized

Every conversation for a given client or topic lives together in one place, instead of scattered across a long list of one-off chats you can never find again.

It works from your real material

You can add reference files — brand guides, past pieces, key documents — to a Project once, and every chat inside it can draw on them. Claude answers from your stuff, not generic assumptions.

Everything sounds like you

Because the same instructions and knowledge sit behind every chat, what comes out is consistent — the same voice and standards across everything you produce.

That "transfer document" you're about to build is exactly what goes into a Project. Here's how to make it.

Have ChatGPT write your "transfer document"

Open ChatGPT in the project or thread where you've done the most work together — that's where it knows you best. Copy the prompt below and paste it in exactly as written.

Paste this into ChatGPT

I want to start using Claude in addition to (or instead of) you. Please help me migrate by synthesizing everything you've learned about me from our work together into a structured "transfer document" I can paste into Claude.

Cover these sections:

1. My voice and style

Tone (formal/casual? warm/direct? declarative/exploratory?)
Sentence rhythm and length patterns
Vocabulary I use often / vocabulary I avoid
How I open and close pieces
Punctuation and formatting preferences (em-dashes, bullet density, headers, italics, sentence-case vs. title-case)
Recurring rules I've given you ("don't do X", "always do Y")

2. My ongoing projects and themes

Major projects we've worked on
Recurring content themes
Specific frameworks, concepts, or terminology I use repeatedly
People, companies, events I reference often

3. My professional context

My role, expertise, and audience
What I'm currently focused on

4. Operating instructions for a future AI

Things to always do when working with me
Things to never do
How I prefer to receive feedback, drafts, lists, structures

Be specific and concrete — quote my actual phrases where possible. Don't generalize. Output the entire transfer document as a single clean markdown text block I can copy and paste into Claude.

ChatGPT will produce a structured document. Copy the entire output — you'll paste it into Claude in the next step.

Set up your Claude Project

Go to claude.ai and sign in (or sign up — a free account works to start).
In the left sidebar, click Projects, then + New Project.
Give it a memorable name (for example, "My Work" or "[Your business] writing").
Open the Project's setup and find the Custom Instructions (sometimes called Project Knowledge) field.
Paste the transfer document there, and save.

From now on, every new chat you start inside that Project reads the transfer document as background. Claude will know your voice and your standing context from the very first message — no re-explaining.

Test the voice — and lock it in

Run the same prompt in both your old ChatGPT thread and your new Claude Project, then compare the two side by side:

Run this in both

"Draft a 200-word LinkedIn post announcing [a recent thing you've published or worked on]. Use my voice."

If Claude sounds like you — you're done. If something's off, just tell Claude plainly, right in the chat:

"This is too formal."
"You opened with a hook I'd never use — I always open with [your typical opener]."
"The cadence is wrong; my sentences are usually shorter."
"You used the word 'leverage' twice — that's a word I avoid."

Claude is good at taking feedback in real time. Once it sounds right, say: "Now update this Project's Custom Instructions to reflect those corrections." Save the new version, and the fix is permanent for every future chat in that Project.

Want to push the voice even further?

Paste a few of your actual past pieces into a chat in the Project and say: "This is how I write. Please update your understanding."
Ask Claude to draft a 2–3 paragraph "voice summary" of how you write. Edit it to your taste, then paste the final version into the Project's Custom Instructions as a permanent reference.