Email subject line length checker
Mobile inboxes cut subject lines around 35 characters. That is the constraint that matters, since most email is opened on a phone.
Numbers appear here once you add text.
- Free, no sign-up
- Counts as you type
- Your text never leaves your browser
Where subject lines get cut
Every client truncates at a different point, and orientation changes it again. These are working approximations rather than fixed rules.
| Client | Visible characters | Note |
|---|---|---|
| iOS Mail, portrait | ~35 | The tightest common case |
| Gmail app, Android | ~35–40 | Varies with device width |
| Gmail, desktop web | ~70 | Preview text follows on the same line |
| Outlook, desktop | ~60 | Depends on reading pane layout |
| Apple Mail, desktop | ~90 | Generous, but rarely the majority of opens |
Front-load accordingly. If the offer, the deadline or the reason to open is not inside the first 35 characters, most recipients will never see it.
The preview text is part of the subject line
Most clients show preview text immediately after the subject, and it is routinely wasted. If you do not set it, recipients see “View this email in your browser” or a stray alt attribute.
Treat subject and preview as one unit of about 35 plus 40 characters. The subject makes the promise; the preview adds the detail that makes it credible.
What moves open rates
- Specificity. “Your March invoice” beats “Important account update”.
- Sender name. Frequently a stronger driver of opens than the subject itself.
- Honesty. Clickbait produces one open and a lasting reputation cost.
- Restraint with emoji. They draw the eye in a crowded inbox and read as spam in a professional one.
- Avoiding all caps and multiple exclamation marks. Both are long-established spam filter triggers.
Common questions
What is the ideal email subject line length?
Under about 45 characters, with the essential message inside the first 35 so it survives mobile truncation. Shorter is usually safer than longer.
Do emojis in subject lines help?
They increase visual distinctiveness in a crowded inbox, which can lift opens for consumer email. In B2B contexts they often read as unprofessional. Test rather than assume, and note that some clients render them as an empty box.