How Long Should an Email Subject Line Be?

Keep the part of a subject line that matters within the first 35 or so characters, and the whole line under about 60 if you can. Many phones show roughly the first 35 to 40 characters of a subject in the inbox list, and desktop inboxes show about 60, though the exact cut depends on the email app, the screen and the reader's settings. The Email Subject-Line Checker counts the characters and flags a subject as "good" up to 35, "may be cut off on phones" from 36 to 60, and "likely cut off" beyond 60.

There is no ideal length that makes people open more email, and this guide does not claim one. The length question is simpler than that: will the reader see the words that tell them what the email is? Below, real subject lines are measured, rewritten and measured again.

Why the cut-off is a range, not a number

No standard sets how much of a subject line an inbox shows. Each email app decides, and the answer changes with the width of the screen, the font size the reader has chosen, whether the app shows a sender name on the same line, and whether the phone is held upright or sideways. That is why the checker uses two working figures, 35 characters for a typical phone and 60 for a typical desktop, and describes the result as likely rather than certain. Treat both as rough guides. If most of your readers use one app, the best check is to send a test to that app.

Real subject lines, measured

Subject line	Characters	Checker verdict
Order #48213 has shipped	24	Good
Your password was changed	25	Good
Your November invoice is ready	30	Good
Last chance: 20% off ends tonight	33	Good
Reminder: the webinar starts at 3pm	35	Good
New guides: title tags, meta descriptions and more	50	May be cut off on phones
Your invoice for November is ready to view in your account	58	May be cut off on phones
Monthly newsletter from the TitleBee team: November edition with new guides	75	Likely cut off on phones and many desktops
We have updated our privacy policy and the terms of service for your account	76	Likely cut off on phones and many desktops

The short ones share a pattern: they say what happened in four to six words. Transactional email (receipts, shipping notices, security alerts) tends to land here naturally, because there is one fact to state. The long ones are long because they carry words that do not help the reader decide anything.

What the reader sees when a line is cut

Taking the first 35 characters of the two longest lines shows the problem:

• "Monthly newsletter from the TitleBe…" The phone shows what kind of email it is and who sent it, both of which the sender name already says, and none of what is in it.
• "We have updated our privacy policy …" This survives better, because the important words came early, but "the terms of service" is lost on a phone.

And the 58-character invoice line becomes "Your invoice for November is ready…" on a phone. Nothing important is lost, because the words that matter came first. That is the point of front-loading: a long subject line is not a problem if the cut falls after the part the reader needs.

Three rewrites

Before	Characters	After	Characters	Verdict after
We have updated our privacy policy and the terms of service for your account	76	Privacy policy and terms updated	32	Good
Monthly newsletter from the TitleBee team: November edition with new guides	75	November: why Google cuts title tags	36	May be cut off on phones
Your invoice for November is ready to view in your account	58	Your November invoice is ready	30	Good

The newsletter rewrite is one character over the phone figure and is still a better subject line than the 75-character original, because the cut, if it comes, takes the last letters of "tags" rather than the whole topic. The verdict is a prompt to check what gets lost, not a fail. A version without the month, "Why Google cuts title tags (and what to check)", is 46 characters: also borderline on phones, but the topic comes first, so the part a phone might hide is only the aside in brackets.

Front-loading, in practice

1. Put the specific word first. "Invoice", "shipped", "password", the article topic, the event time. Generic openers ("Monthly update", "News from", "Just a quick note") use up the visible space.
2. Drop what the sender name already says. The inbox shows who the email is from beside the subject. "From the TitleBee team" repeats it.
3. Put dates and numbers where they help. "Webinar starts at 3pm: link inside" (34 characters) puts the time inside the phone figure. A date at the end of a long subject is the first thing a phone hides.
4. Read the first 35 characters on their own. If they make sense without the rest, the line works on a small screen whatever its full length.

The preheader shares the space

Most inboxes show a line of preview text after or under the subject, often called the preheader. If you do not set it, the email app takes the first text it finds in the email, which is sometimes "View this email in your browser" or an image's alt text. Setting it on purpose gives you a second short line to use. Two habits help:

• Do not repeat the subject in the preheader. Use it for the next most useful fact ("Due 30 November, pay online in two minutes").
• Keep the most important words early here too, because on a narrow screen the subject and preview text may share one line and the preview is what gets cut first.

The checker measures the subject only. You can paste a preheader into it to count its characters, but the 35 and 60 figures were chosen for subjects, and how much preview text an inbox shows varies even more.

Emoji and special characters

The checker counts characters the way most software stores them, so an emoji usually counts as two. "🎉 New guides" comes out at 13 characters against 10 for "New guides": the emoji and the space after it add three. Email apps differ in how wide they draw emoji, so treat the count as approximate when your subject contains them. Accented letters count as one character each: "Café menu" is 9.

What the checker does not cover

• The exact cut in a specific app. It uses two typical figures, not each app's real width.
• Pixel width. Inboxes use proportional fonts, so a subject full of capitals and wide letters gets cut sooner than the character count suggests. For search titles the Headline Pixel Counter measures width in pixels; inboxes vary too much for one pixel figure to be useful.
• Whether the email arrives. Length has nothing to do with spam filtering. The checker also lists words that can read as junk mail, and why that list is not a spam filter is covered in do spam words in a subject line send email to spam?
• Open rates. No length guarantees more opens, and the checker makes no prediction about them. Whether people open an email depends far more on whether they want email from you and whether the subject tells them what is inside.
• Tone and accuracy. A subject line that promises something the email does not deliver may get opened once and ignored after that.

Write the subject that describes the email, put the specific words first, and use the checker to see where a phone is likely to cut it.