How An Em Dash Reveals Your Use Of ChatGPT

If you're using ChatGPT to write for you and think nobody can tell, you might want to think again. A single piece of punctuation is giving the game away, making your use of the chatbot incredibly obvious.

From crafting the perfect pickup line to drafting a resignation email, an estimated 300 million people use ChatGPT every week. But how is everyone catching on?

The Telltale Sign of AI Writing

The secret lies in a small but significant punctuation mark: the em dash (—).

ChatGPT has a tendency to frequently use the em dash—that symbol slightly longer than a hyphen used to mark a break in a sentence. When users copy and paste text directly from the AI into emails, messages, or documents, this stylistic quirk comes along for the ride.

The Social Media Verdict The ChatGPT Hyphen

The problem is that most people don't use the em dash in their everyday writing, reserving it for more academic or formal contexts. Its presence in a casual email or social media post is a dead giveaway. This has become so well-known that people on social media have even nicknamed it the “ChatGPT hyphen.”

The observation is a hot topic online. One user on X noted:

Nothing says “written by ChatGPT” more than the em dash —

— Amy Wu Martin (@amytongwu) June 13, 2025

Another user gave this advice:

If I see an em dash (this thing: — ) in a post

I am 100% going to assume it was written by ChatGPT

— CrispinCapital (@CrispinCapital) June 21, 2025

How to Use ChatGPT Without Getting Caught

So, if you're a regular user of copy-and-paste, you're not fooling anyone. They know.

Next time you use ChatGPT, take a moment to review the output. The simplest fix is to manually remove the em dash before you send your message. If you're feeling particularly lazy, you can even ask ChatGPT to do it for you with a follow-up prompt like, "remove the em dashes from that text."

Now that you know, you'll never look at that particular piece of punctuation the same way again.