Subject Line Ruler by Loop is a free Chrome add-on that helps users write visible subject lines in any inbox, without unexpected cuts or truncation.

Have you ever spent a lot of time crafting the perfect subject line, only to see it get cut off in email inboxes or mobile notifications? This add-on aims to solve that problem once and for all. Instead of focusing on character or word limits, Subject Line Ruler measures the length of your subject line in pixels.

By considering the pixel length of each character, including emojis, this extension accurately measures the actual visual length of your subject line. If it exceeds a certain number of pixels, it will be automatically truncated.

Using Subject Line Ruler is simple. Just install the extension, click on its icon to test the length of your subject line, and receive instant feedback.

For users of Klaviyo, there's an added bonus. After installing the extension, you'll find a button below the "subject line" field in your Flow and Campaigns. Clicking it will measure the length of the subject line you just wrote.

Say goodbye to cut-off subject lines and start writing impactful messages with Subject Line Ruler by Loop.