Email subject line length checker
Type something and the most frequent words show up here.
A subject line is cut around 60 characters on desktop and around 35 on mobile, and mobile is where most email is opened. Front-load accordingly.
How to use the email subject line length checker
Thirty-five characters is roughly five words, which is far less room than people assume when writing at a desk. The preview text beside it is the underused half: most clients show 40 to 90 characters of the email body after the subject, and leaving that to be filled by "View this email in your browser" wastes the most valuable line in the inbox. Set it deliberately with a preheader. Two things to avoid regardless of length: ALL CAPS and multiple exclamation marks both correlate with spam filtering, and the RE: or FW: prefix on a message that is neither is a trust cost that outweighs any open-rate gain.
Questions
Under 35 characters to survive mobile truncation. Sixty is the desktop limit.
The 40 to 90 characters of body text shown after the subject. Set it with a preheader or the client picks the first thing it finds.
Mixed evidence, and they render inconsistently across clients. Test rather than assume.
It correlates with spam scoring, along with multiple exclamation marks. Not worth the risk.
Not always, but a subject that is cut mid-word always reads worse than one that fits.