Email Subject Line Length: How Many Characters Show?

Why length matters

The subject line is the first thing a recipient sees, and often the only thing. If it is cut off, the part that is lost may be the point. Different devices and email programs cut at different lengths, so a line that looks fine on a desktop can be truncated on a phone.

Most people read email on a phone, so the mobile cut-off is the one to plan for first. A line that carries its message in the opening words works everywhere.

How many characters show

A device test described by BuzzStream, based on real phones and tablets, found that Gmail on iPhone and Android showed about 37 characters, Gmail on iPad about 39, Outlook on iPhone about 38 and Apple Mail on iPhone 14 about 48. Apple Mail on an iPad showed only about 31. On desktop, Gmail and Apple Mail show roughly 60 to 70 characters and Outlook 50 to 60.

These numbers depend on the device, the app, the font and the settings, and they change with updates, so treat them as typical values. The practical conclusion is that the first 30 to 40 characters matter most.

What the data says about long lines

BuzzStream also analysed more than six million subject lines sent through its platform in digital PR campaigns. It reported that lines of more than 71 characters had the highest open rate of any length group, at about 40.7 per cent, and that lines of 9 to 13 words reached about 40.2 per cent.

The author’s own conclusion is that length alone is not the lesson, and that wording and structure matter more. The data comes from one platform and one kind of email, so do not assume it applies to newsletters or sales mail.

A practical target

A sensible approach is to put the main hook in the first 30 to 40 characters and let the line run longer if it adds something. Under 33 characters shows in full on nearly every device but leaves little room. Between 40 and 60 is a common middle that works on desktops and shows the start on phones.

Test with your audience. Send two versions of a line to small groups and compare the open rates, and keep the result for the next campaign.

Writing a subject line that works

Be specific. A line that states what is inside, such as a date, a number or a clear benefit, tells the reader why to open. Avoid vague teasers and misleading promises, which cost trust. Avoid long strings of capital letters and exclamation marks, which look like spam and can trigger filters.

Write the line for one reader. If you can picture a person who would care about it, the words are usually better than if you write for everyone.

Preview text

Many email programs show a second line of grey text after the subject, called the preview text. It comes from the start of the email, or from a field you set. Use it to add detail that did not fit in the subject, and avoid repeating the subject.

The preview text has its own length limits, which vary by program. Check it on a phone, because a long line of links or “view in browser” text can fill it.

Emoji and special characters

Emoji can make a line stand out, but they use space and may display differently across programs. An emoji counts as one character in a plain counter, though it takes the room of two or three letters on screen. Use at most one or two, and place them where losing them would not change the meaning.

Non-Latin text is wider, so a Japanese subject line is cut at fewer characters than an English one. Check the display in the programs your readers use.

An example, step by step

Take a draft line: “Our Autumn Sale Has Started and There Are Many Great Offers Waiting for You Inside This Email”. It has 93 characters, and on a phone only about the first 37 would show. The offer is hidden.

A rewrite such as “Autumn sale: 20% off until Sunday” has 33 characters and shows the point on every device. If the details do not fit, move them to the preview text.

Testing your own audience

General figures are a starting point. Your readers use particular programs and devices, and your emails have a particular tone. An A/B test on two subject lines, sent to equal halves of a small list, shows which works better for you.

Change one thing at a time, such as length or the first word, and keep notes. After a few tests you will know your own best range, and that is worth more than any general rule.

A quick checklist

• Put the hook in the first 30 to 40 characters.
• Count the line and look at it on a phone.
• Write a preview text that adds, not repeats.
• Use emoji sparingly.
• Test two versions on a small group.

Email programs change, so recheck the display from time to time and rely on your own results as well as general figures.