Email Subject Line Length Checker
Type your subject line and see exactly how it appears in Gmail, Outlook, Apple Mail, and on mobile. Truncated subject lines get ignored.
Most email clients display between 30 and 80 characters of a subject line before cutting it off with an ellipsis. The exact limit depends on the client, the device, and the window size.
Mobile has made this more important than ever. Over 60% of emails are now opened on a phone, where the subject line preview can be as short as 30 characters. A subject line that looks fine in Outlook on a desktop may display as nothing but the first few words on an iPhone. The safest approach is to put the key message in the first 40 characters.
How we work it out
Each email client has a typical character limit based on standard window sizes and fonts. The preview shows your subject line trimmed to that limit with an ellipsis appended. Limits used: mobile 30 characters, Gmail mobile 40, Outlook desktop 60, Gmail desktop 70, Apple Mail 80. These are approximations — actual limits vary with window size and device settings.
Questions
What is the ideal subject line length?
40-60 characters is the most commonly cited sweet spot. It is short enough to display in full on most desktop clients, and long enough to be descriptive. Under 40 characters is the safest option if a significant portion of your recipients are on mobile.
Do these limits vary?
Yes. The limits in this tool are based on typical window sizes and default settings. A user with a narrow inbox pane or a smaller font size may see fewer characters. The figures here are useful guidelines, not hard guarantees.
Does subject line length affect open rates?
Research is mixed, but the consistent finding is that truncated subject lines hurt open rates because the recipient cannot tell what the email is about. Front-loading the most important words matters more than the total character count.
Between drafts. Officially reviewing engagement metrics.