Email subject line length: see where it’s cut off

For the example email with a 76-character subject line, this is how much of the subject each screen shows before it’s opened:

How we measure: each screen is drawn at its real size (an iPhone screen is 390 by 844 points; Gmail on a laptop is a 1280-pixel-wide window) in the fonts those apps use, and the tool counts how many characters fit before the app cuts them off. Your phone model and text size setting can move it by a few characters. Measured 16 October 2026.

So keep the part that matters inside the first 40 characters: that’s what a phone notification shows. Anything after that is a bonus in the Gmail app and on a laptop.

Most guides give one fixed count: ActiveCampaign says 37 characters for the Gmail app on an iPhone and 33 on Android, Twilio says 33 to 41 for an iPhone, Validity says just 25 to 30 on mobile, and Courier about 35. They disagree because the real limit is width, not a count: a line of i’s and l’s takes far less room than a line of W’s and M’s. This tool measures your actual words.

Email itself allows very long subject lines (the email standard’s line limit is 998 characters), so you won’t hit a hard limit. What matters is how much shows: about 40 characters on a phone notification and a little more in the Gmail app.

Yes, every inbox cuts long subject lines to fit. This tool doesn’t draw Outlook yet, so it doesn’t give an Outlook number.