Email subject line tester

An email subject line tester scores your subject line before you send it. Omnisend’s tester rates it from 0 to 100% and checks its length, wording, and scannability. It also shows how the line will look in a desktop and mobile inbox, so you can fix it before it goes out.

It checks for negative words that can make your email look spammy or put readers off, and shows the result in the Wording section. It also flags helpful words, like “last chance,” that tend to make people more likely to open. For deliverability, your sender reputation matters more than any single word.

Start with the tips under your score. Most subject lines improve by getting shorter, adding a number, using sentence case, or swapping a negative word for a helpful one. Test again after each change to see which tweak moves your score the most, and check the mobile preview before you send.

Yes. An emoji can help your subject line stand out in a busy inbox. Use one or two, place them next to the words they support, and keep the meaning in the words, since some inboxes show emojis differently. More ideas in our guide to emojis for email.

Yes. The subject line tester is free, and you don’t need an account to use it. Test as many subject lines as you like. If you need fresh ideas to test, try our free subject line generator, then run your favorites through the tester.