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Email Subject Line Length
There is no official character limit you'll hit in practice. The real limit is how much the inbox shows before it cuts your line off. Drag the inbox below to see exactly where your subject line gets truncated.
See where your line gets cut
Only the first 0 of 57 characters show. The reader sees: “…” and never sees “Your spring order ships free, plus a surprise gift inside”.
The short answer
Aim for about 30–50 characters, and put the important words in the first 30–35. That usually shows in full on desktop and keeps the key part visible on phones, where most email is opened.
Truncation is measured in pixels, not characters. Wide letters (m, W) use more room than narrow ones (i, l, t), which is why the demo measures your actual text rather than counting.
Is there a hard character limit?
The email standard (RFC 5322) recommends lines of no more than 78 characters and caps them at 998, and long subjects can wrap across header lines, so you won't hit a technical wall. Some email platforms set their own limits, often around 150 characters. None of that matters as much as what fits on screen.
Short or long?
Short lines (under ~30 characters) are scannable and suit cold emails and follow-ups. Longer lines can work when every word adds information, as long as the opening words make sense alone. Test both with your list.
Typical visible characters by inbox
Rough ranges only: they vary with the app, font size, screen size and whether the sender name and date share the line.
| Where it's read | Roughly visible | What to do |
|---|---|---|
| Phone, portrait | ≈ 30–45 characters | Front-load the key words |
| Tablet / narrow window | ≈ 45–65 characters | Most 50-character lines fit |
| Desktop list view | ≈ 60–90 characters | Subject shares a line with the preview text |
| Smartwatch notification | ≈ 20–25 characters | The first three words carry it |
Frequently asked questions
How long should an email subject line be?
About 30–50 characters (roughly 4–9 words) works for most campaigns. Keep the essential words in the first 30–35 characters because phones cut off the rest.
What is the character limit for an email subject line?
Technically, very long subject lines are allowed: the email standard recommends 78 characters per header line and caps a line at 998, with folding for longer headers. Email platforms often set a practical limit around 150 characters. The visible limit in the inbox is much shorter.
Do emojis count toward subject line length?
Yes. An emoji takes about the width of one or two characters on screen, and in some systems counts as two characters. Some older clients may show a blank box instead.
How many characters show on iPhone?
In Apple Mail on a typical iPhone in portrait, roughly 30–45 characters of the subject are visible depending on the model, text size and letter widths. Use the slider above to test your own line.