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Email Header Size Guide

Complete reference for email header dimensions. Covers logo headers, standard banners, hero sections, and preheader bars. Includes a custom size checker, email type recommendations, and Outlook compatibility tips.

About this tool

The email header is the first thing recipients see when they open your email. Getting the dimensions right means it looks professional across every email client — from Gmail on a phone to Outlook on a desktop. Too tall and you push content below the fold. Too short and your branding gets lost. Wrong width and things break in unexpected ways.

This guide covers four types of email headers: preheader utility bars, logo bars, standard header banners, and hero sections. Each has a different purpose and optimal size. You'll also find a custom size checker that validates your specific dimensions and gives you feedback on compatibility.

For the complete picture on email image dimensions, also check our email banner size guide (focused on campaign-specific banners) and email signature size guide (for the other end of your email). Make sure your total email stays under clipping limits with our email word counter.

Once your header is sized right, use our dark mode preview to make sure it doesn't look weird on dark backgrounds, and our contrast checker to verify any text overlays remain readable.

Frequently Asked Questions

What is the standard email header size?

The most common and universally compatible email header size is 600 × 120-200px. A 600px width works in every major email client, and 120-200px height gives you enough room for branding without pushing content too far down. For a simple logo bar, 600 × 60-80px is standard. For hero-style headers, 600 × 300px is the maximum before you start losing recipients to scroll fatigue.

Why is 600px the standard email width?

600px became the standard because Microsoft Outlook's Word-based rendering engine caps content at around 600px. While modern clients like Gmail and Apple Mail can display wider content, designing at 600px ensures compatibility with everyone. Some modern templates use 640px or even 700px, but 600px is the safe choice that works everywhere without exceptions.

How tall should my email header be?

It depends on the email type. For newsletters: 60-120px (logo + issue info). For promotional campaigns: 150-200px (branded banner). For product launches: up to 300px (hero with CTA). For transactional emails: 40-60px (just a logo). The key rule: your header should be short enough that recipients can see the beginning of your content without scrolling, especially on mobile where screen height is limited.

Should I use a header image or HTML text?

Use a combination. Keep your logo as an image but use live HTML text for headlines, taglines, and navigation links. This way, if images don't load (Gmail blocks images by default for new senders), recipients still see your key message. Pure image headers appear as blank boxes when images are blocked, which is a terrible first impression.

How do I make my header look sharp on iPhone/Mac?

Apple devices have retina (2x) screens. Design your header at double resolution — for a 600×120 header, create the image at 1200×240px and set the HTML width attribute to 600. The image displays at the smaller size but uses the extra pixels for crispness. You can use lower JPEG quality (60-70%) for retina images since the extra detail compensates for compression.

Does my header need to work in Outlook?

If any of your recipients use Outlook desktop (very common in B2B), yes. Outlook uses Microsoft Word's rendering engine, which doesn't support CSS background-image, flexbox, or grid. Use table-based layouts, inline styles, and set explicit width/height attributes on all images. For background images in Outlook, use VML (Vector Markup Language) — it's ugly code but it works.

Should I use the same header for every email?

Consistent branding (same logo, same colors, same position) builds recognition — recipients should instantly know who the email is from. But the header style can vary: newsletters get a clean logo bar, promotions get a bold banner, and transactional emails get a minimal header. The logo and color scheme should be consistent; the size and content can change based on the email's purpose.

What about dark mode email headers?

Dark mode can invert your header colors unexpectedly. Email clients like Apple Mail and Outlook can change background colors and sometimes invert images. Transparent PNGs are especially risky — a logo on a transparent background looks great on white but may disappear on dark. Solutions: add a subtle background to transparent logos, test in dark mode before sending, and consider using our dark mode preview tool to catch issues.

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