What is the difference between a subject line and a preheader?

The subject line is the main title of your email. The preheader (or preview text) is the short snippet of text that appears immediately after the subject line in most modern inboxes. Optimizing both is the key to high open rates.

Why does my subject line look different on Outlook vs. Gmail?

Different email clients use different widths for displaying text. Outlook Desktop usually allows for more characters, while Gmail Mobile and iPhone Mail are much stricter. Pixedra helps you visualize these differences in one click.

Is my email data private?

Yes. Like all Pixedra utilities, this tool runs 100% client-side. We do not record or save the subject lines you test.

Free Email Subject Line Tester & Visualizer

Don't let a truncated subject line ruin your open rates. Pixedra’s Email Subject Line Previewer simulates the real-world inbox experience. Test your subject lines and preheader text across iPhone, Gmail Mobile, and Outlook Desktop instantly. Ensure your message lands perfectly without being cut off by character limits. 100% browser-based privacy—your email content is never stored.

Email Content

Sender Name

A/B Test Mode

Subject Line

22 / 60

Preheader Text

46 / 90

Feedback

Looks good on major clients!

iPhone Mail (Lock Screen)

Your Appnow

Your Weekly Newsletter

This is a preview of the great content inside.

Gmail (Mobile Inbox)

Your App

Your Weekly Newsletter - This is a preview of the great content inside.

10:30 AM

Outlook (Desktop)

Your App

Your Weekly Newsletter

This is a preview of the great content inside.

You spent hours writing the perfect email, but will your subscribers actually open it? On mobile devices, long subject lines get truncated (cut off) with ..., killing your open rates. Pixedra’s Subject Line Previewer simulates the inbox experience of your subscribers. See exactly how your Sender Name, Subject Line, and Preheader Text appear on iPhone Lock Screens, Gmail App, and Outlook Desktop. Optimize your character count to ensure your message lands perfectly.

How to use the Email Preview Tool

Enter Sender Name: Type your brand name to see how much space it takes up on mobile.
Draft Subject Line: Write your hook. Watch the Character Counter—aim for 40-60 characters for mobile optimization.
Add Preheader: This is the "preview text" shown below the subject. Use it to support your subject line (Limit: 90 chars).
Check Previews: Toggle the Outlook Dark Mode and check the iPhone Lock Screen view to ensure nothing vital is cut off.

Character Limit Best Practices

What is the ideal Subject Line length in 2026?

iPhone (Mail App): Truncates after ~41 characters (Portrait mode).
Gmail (Android): Truncates after ~70 characters.
Desktop Webmail: Shows 60-100 characters.

The Golden Rule: Keep your most important keywords within the first 40 characters. Use the Preheader Text to expand on the details.

Why Preheader Text Matters?

The "Second Subject Line"

Many marketers forget the Preheader (Preview Text). On an iPhone Lock Screen, the preheader takes up more space than the subject line!

Bad Preheader:

"View this email in your browser..."

Good Preheader:

"🔥 Flash sale ends in 3 hours. Don't miss out."

Use our tool to verify that your preheader connects seamlessly with your subject line.

High-Converting Subject Line Examples (2026 Trends)

Resignation Email:

"Resignation - [Your Name]" or "Polite Notice of Resignation"

Post-Interview Follow-up:

"Thank you - [Job Title] Interview" or "Following up on my application"

Cold Outreach:

"Quick question regarding [Topic]" or "[Name], checking in"

Frequently Asked Questions

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