Email Subject Line Length Checker

Email Subject Line Length Checker measures your subject line in both characters and rendered pixels, then shows exactly how it will look in mobile and desktop inboxes. As you type, it counts characters, words, and emojis, estimates the real pixel width, and flags when a subject is heading into truncation territory.

Subject lines that truncate lose their impact right when recipients decide whether to open. This tool turns a common guess into a measurable check, with live preview bars that show where Gmail, Outlook, Apple Mail, and mobile clients will cut your text off.

• Live character count: See characters, words, and emoji count update as you type.
• Rendered pixel width: Canvas-based measurement estimates how wide the subject actually renders in the inbox.
• Truncation previews: Two preview bars show your subject clipped at mobile and desktop inbox widths.
• Client limits reference: A table of approximate character and pixel limits for major email clients.
• Instant verdict: Clear pass, warning, or fail feedback with a visual safety gauge.

1. Type or paste your subject line into the analyzer. The stats update live as you type.
2. Pick the font and size that best match how your recipients read email, since this changes the pixel width.
3. Watch the verdict and gauge to see if your subject fits the safe zone.
4. Check the two preview bars to see how the subject will look clipped on mobile and desktop.
5. Shorten or reorder the subject until it fits comfortably, keeping key words at the front.

Example 1: "Your 50% off summer sale starts now" measures about 36 characters and roughly 300 pixels at 17px Arial — it sits safely inside the optimal zone and fits fully on most mobile inboxes.

Example 2: "Last chance to claim your exclusive 25% off everything in our summer collection before midnight" measures around 90 characters and over 700 pixels, and the tool flags it as likely to truncate in every client.

• More opens: Full, untruncated subjects get the message across before the recipient decides.
• Better mobile UX: Keep the entire subject visible on small screens where space is tightest.
• Confident edits: See the measurable impact of shortening or moving words around.
• Works for any client: Pixel measurement covers rendering differences between Gmail, Outlook, and Apple Mail.
• 100% free and private: No sign-up, no data stored, everything runs in your browser.