Email Subject Line Preview Tool

Email Subject Line Preview Tool shows you exactly how your sender name, subject line, and preheader will look inside real inboxes. Type once and watch your email render as a Gmail, Outlook, and Apple Mail inbox row, plus a compact mobile preview — complete with the truncation points each client applies.

Most opens happen on mobile and the decision to open is made in under a second, so the way your email appears in the preview matters. This tool gives you a realistic, client-accurate look before you send, so nothing important gets cut off.

• Live client previews: Realistic Gmail, Outlook, Apple Mail, and mobile inbox mockups update as you type.
• Truncation detection: A cut-off badge appears when the subject overflows the inbox row width.
• Sender + preheader controls: Preview the full inbox line, not just the subject.
• Client-accurate styling: Each mockup uses the layout and font family of the real client.
• Character stats: Track subject and preheader length while you edit.

1. Enter your sender name — this is what appears bold on the first line of the inbox.
2. Type your subject line and watch all four previews update instantly.
3. Add your preheader text to see how the second preview line fills out.
4. Check the cut-off badges to see which clients would truncate your subject.
5. Shorten or reorder until the subject reads fully in every preview.

Example 1: Sender "Acme Inc.", subject "Your 50% off summer sale starts now", and a short preheader. The subject fits fully in all previews, so the offer is visible at a glance on desktop and mobile.

Example 2: A long subject with a matching preheader overflows the mobile row. The tool flags the cut-off point, and the marketer moves the offer to the front of the subject so it survives truncation.

• Send with confidence: Know how your email renders before it reaches real inboxes.
• Fewer wasted opens: Keep the full message visible where recipients decide to click.
• Client-aware design: See the differences between Gmail, Outlook, and Apple Mail instantly.
• Better preheaders: Preview the second line so your subject and preheader work as a team.
• 100% free and private: No sign-up, no data stored, everything runs in your browser.