Mailchimp's help pages state no hard character cutoff for subject lines. Its guidance is to use no more than 9 words and 60 characters, no more than 3 punctuation marks and no more than 1 emoji. A built-in subject line helper checks your line against those tips as you type and suggests changes.
60 characters is advice, not a wall
You'll see 60 characters quoted as Mailchimp's limit all over the place. Look at the help pages and it's a recommendation. Mailchimp suggests no more than 9 words and 60 characters, because shorter is often better, especially for people reading on a phone. Nothing in the help pages says the Subject field cuts off or rejects a longer line.
So the real question isn't what Mailchimp will accept. It's what your reader will see.
Mailchimp's subject line guidance in one table
| Item | Guidance | Source |
|---|---|---|
| Words | No more than 9 | Mailchimp guidance |
| Characters | No more than 60 | Mailchimp guidance |
| Punctuation marks | No more than 3 | Mailchimp research |
| Emojis | No more than 1 at a time | Mailchimp research |
| Recent subject lines shown | Last 5 | Subject line helper |
Too much punctuation can make an email look like spam, which is why Mailchimp suggests keeping it to three marks. Emojis should support your words rather than replace them, and since different operating systems render emojis differently, Mailchimp says to test them before you send.
What the inbox shows is the shorter limit
Mailchimp Help sets 60 characters as a recommendation, and Brevo's subject line guide adds the useful bit: inboxes cut the line off at different points. Brevo lists display limits by client of Gmail 77, Outlook 60, Yahoo 47 and Hotmail 45 characters. So a 60-character line can still be trimmed in some inboxes, and the end of your sentence is the part that goes missing.
My rule: put the words that matter in the first 40 or so characters, and let anything after that be a bonus.
A quick worked example
Take 'Our biggest ever autumn sale starts today, with new discounts across every single product range'. That's 15 words and well over 60 characters, and most inboxes will cut it mid-thought. Trim it to 'Autumn sale starts today: new offers on every range' and you're at 9 words, under 60 characters, with one punctuation mark and the point up front.
Using the subject line helper
Start typing in the Subject field and a subject line helper appears. It shows a green check mark for each tip you're following, or an alert with a suggested change when you're not. Its tips are based on how hundreds of millions of emails sent through Mailchimp performed.
There's also a 'recent subject lines' link that lists your last 5 subject lines with how each one did, so you can compare a new line against your own history rather than guessing.
Writing and testing your line
- In a regular email, open the Subject section of the email checklist.
- Enter the Subject and the Preview Text, then click Save. Preview text appears next to the subject line in the inbox, so use it to finish the thought.
- Watch the helper's checks as you type, and trim words until you're at 9 or fewer.
- Add a merge tag for the recipient's name or location if it fits. Mailchimp says personalised subject lines help most users.
- If you're unsure between two versions, run an A/B test.
An A/B test sends versions that differ only in subject line to random parts of your audience, then automatically sends the winning version to everyone else. Multivariate testing is a separate feature on a higher plan. For more on testing lines, my guide to testing and improving subject lines goes deeper.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
How another email platform frames length
Brevo recommends subject lines no longer than 60 characters or 6 to 8 words, a slightly tighter word count than Mailchimp's 9. If you're weighing the two platforms, or others, my comparison of MailerLite and Mailchimp covers the bigger differences.
My advice for your next subject line
Write it short, front-load the point and let the preview text do the rest. Aim for 9 words and 60 characters, but think of 45 as the safe zone for every inbox. Keep to one emoji and three punctuation marks at most. If you're stuck for ideas, my subject line prompt pack has starting points.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
What is the Mailchimp subject line character limit?
Mailchimp's help pages don't state a hard cutoff. They recommend no more than 9 words and 60 characters.
How many emojis should I use?
No more than 1 at a time, according to Mailchimp's research.
How much punctuation is too much?
Mailchimp suggests no more than 3 punctuation marks.
Does Mailchimp check my subject line?
Yes. A subject line helper appears as you type and shows which tips you're following.
Where do I add preview text?
In the Subject section of the email checklist, next to the Subject field.
