Type your subject line and preview (preheader) text and see, client by client, exactly how much of each will actually display before getting cut off with an ellipsis — across Gmail, Outlook, Apple Mail on iPhone, and Yahoo Mail.
Every major email client allocates a different amount of horizontal space to the inbox list view, and that space is split between the subject line and the preview text (sometimes called the preheader) shown right after it — so the same subject and preview combination can display completely on a Gmail desktop screen while getting cut off mid-word on an iPhone's Mail app. Screen width, font choice, and whether the client shows a sender name, icons or labels alongside the subject all affect exactly where the cutoff falls.
This tool uses commonly cited approximate character limits for five major client/device combinations — Gmail desktop, Gmail mobile, Outlook desktop, Apple Mail on iPhone, and Yahoo Mail — and shows a live progress bar for each as you type, turning red once you've likely exceeded what that client will display in full.
The preview text is prime real estate that many senders leave to chance, letting the email client just grab the first line of the body (often something unhelpful like 'View this email in your browser'). Writing preview text deliberately — as a second, complementary line to your subject, rather than a repeat of it — gives recipients a stronger reason to open, and this tool helps you fit that message within the space each client actually gives you before it's chopped off.
No — they're commonly cited approximations. Actual cutoff points shift slightly based on font rendering, screen size, zoom level, and whether the client shows extra UI elements like folder labels next to the subject. Treat the bars as a strong guide, not a pixel-perfect guarantee.
The subject line is the primary line recipients see; the preview text (or preheader) is the secondary snippet shown right after it in most inbox list views, often pulled automatically from the first line of your email body unless you set it deliberately.
Mobile screens are narrower, and Gmail's mobile app also reserves space for the sender name and preview snippet on the same line, leaving noticeably less room for the subject itself compared to the wider desktop inbox view.
It depends on your audience — if you know most of your recipients use one specific client (say, mostly Gmail), it's reasonable to prioritize that cutoff. For a general audience, aiming for the more conservative mobile limits keeps your message intact almost everywhere.
No — this tool is purely about character length and truncation. For spam-related wording and formatting checks, use the Email Subject Line Tester or Spam Score Checker.