Email Subject Line and Preview Text Tester
Type your subject line and preview text to see how they'll look, and where they'll be cut off, in iPhone Mail, the Gmail app, Gmail on a computer and Outlook. Tips update as you type.
How it looks
Previews use each app's typical width and font size, so the cut-off point is close to what readers see. Exact results vary with screen size, text size settings and the reader's other emails.
Tips for subject lines and preview text
Put the important words first. Phones show roughly 30–45 characters of a subject line before cutting it off.
Always write preview text. If you don't, the inbox shows the first words of your email instead, which is often "View in browser" or an image's alt text.
Avoid ALL CAPS, piles of !!! and spammy phrases. They look pushy to readers and to spam filters alike.
How to use the Subject Line Preview
- Type the sender name your readers will see.
- Write your subject line and preview text.
- Check the four inbox previews to see where each is cut off.
- Follow the tips under the boxes, then adjust until the important words show everywhere.
Writing subject lines that get opened
Lead with the reason to open: the offer, the news, or the question, in the first 30 to 40 characters.
Be specific: "Your order ships Tuesday" beats "An update about your order".
Use the preview text as a second line of your pitch rather than repeating the subject.
Test two versions on a small part of your list if your email platform supports it, then send the winner to everyone else.
Why preview text matters
Most inboxes show a line of preview next to or under the subject. If you don't set one, the inbox fills it with whatever comes first in your email, which is often "View this email in your browser" or an image description.
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Frequently asked questions
How long should an email subject line be?
Aim for 30 to 45 characters so the whole subject shows on phones, and put the most important words first.
What is preview text (preheader)?
The short line shown after or under the subject in the inbox. If you don't set it, inboxes show the first words of your email instead.
How long should preview text be?
Roughly 40 to 100 characters. Use it to add to the subject, not repeat it.
Do emojis work in subject lines?
Most modern inboxes show them, and the previews here use your device's emoji. Use them sparingly and never in place of the key words.
How do I set preview text?
Most email platforms have a "Preview text" or "Preheader" field next to the subject line. If yours doesn't, add a short hidden line at the very top of your email.
Do subject lines get cut off on computers too?
Less often, but Gmail on a computer shows the subject and preview text on one line, so long subjects push the preview text out of view.