Email Banner Size and Email Dimensions: 2026 Cheat Sheet

Email dimensions are one of the few areas of email design with right answers. Get the width, image sizes and file weights right once, bake them into your templates, and every campaign after that renders cleanly. Get them wrong and you get blurry heroes, 4MB banners and headlines that shrink to unreadable on a phone.

This is the cheat sheet: the standard email width, the email banner size for headers and heroes, image sizes for product grids, and the export and file-size settings that keep it all sharp and fast in Klaviyo, Gmail, Outlook and Apple Mail.

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What is the standard email banner size?

Design email banners 600px wide, the standard email template width. Header banners run 600 x 80–200px, hero banners 600 x 300–600px. Export every image at 2x (1200px wide) so it stays sharp on high-resolution screens, set it to display at 600px, and keep each file well under 1MB.

Most “banner size” confusion comes from mixing up three numbers: the display size (how big it appears in the email), the export size (the pixel dimensions of the file) and the file size (the kilobytes). The table below separates them.

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Email dimensions cheat sheet

Element	Display size (px)	Export size (2x)	Target file size
Email template width	600 wide	n/a	Keep the code under ~85KB (Gmail clipping)
Header / logo bar	600 x 80–200	1200 x 160–400	Under 100KB
Logo inside header	120–250 wide, 40–80 tall	2x	Under 50KB
Announcement strip	600 x 40–60	1200 x 80–120	Better as live text
Hero banner (landscape)	600 x 300–450	1200 x 600–900	150–400KB
Hero banner (square/portrait, mobile-first)	600 x 600–750	1200 x 1200–1500	200–500KB
Full-width body banner	600 x 200–400	1200 x 400–800	Under 300KB
Two-column product image	~270 x 270	~540 x 540	Under 100KB each
Three-column product image	~170 x 170	~340 x 340	Under 60KB each
Animated GIF (full width)	600 wide	1x–1.5x only	Under 500KB (see our GIF guide)
Footer	600 x 100–250	Mostly live text	Minimal
Email signature banner	300–600 x 80–150	2x	Under 100KB

Column image widths assume a 600px template with standard padding. Your exact figure depends on your padding and gutters, so measure the column in your builder and design to that.

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Why email width is 600px

Klaviyo’s help centre states that “the default width of every template is 600px”, and explains why: historically, the viewport of popular desktop email clients was between 500 and 600px, and sticking to 600px helps emails render well on mobile. Klaviyo recommends not increasing the width “unless this is required for a more advanced layout.”

In practice:

• 600px is the safe standard for ecommerce. It fits desktop reading panes without horizontal scrolling and scales cleanly on phones.
• 640–700px is used by some brands for a more spacious desktop look. It works in modern clients but gains little, because most ecommerce email is read on mobile, where everything is scaled to the phone’s width anyway.
• Anything wider risks side-scrolling in Outlook’s reading pane and awkward scaling elsewhere.

Klaviyo also scales oversized images down to the template width automatically, with the aspect ratio preserved, so an image uploaded at 1200px will display at 600px without extra work.

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Klaviyo’s image specs (as of September 2026)

From Klaviyo’s “email images best practices” article:

• Formats: JPEG, PNG and GIF. Static WebP is converted to PNG; animated WebP is not supported.
• Full-width image width: between 600 and 1000px, and less than 2000px tall.
• Resolution: 72dpi.
• File size: 1MB or smaller recommended; 10MB maximum.
• Compression: Klaviyo compresses images automatically, except GIFs.
• Sharpness: Klaviyo suggests inserting an image at 2x the display size and scaling it down in the template for crisper results.

Klaviyo adds a practical caveat: full-width images at 72dpi will often be larger than 1MB, so you are balancing quality against load speed. Compress before uploading (TinyPNG, Squoosh or your design tool’s export settings) rather than relying on the platform to do it.

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Height, the fold and the first screen

Width is fixed; height is a design decision. On a typical phone, the first screen of an email shows roughly the top 500–650px of a 600px-wide design once it has been scaled down. Everything that has to land before a scroll needs to fit in that space: logo, headline, hero and ideally the first CTA.

That is why we push back on 200px headers and 900px-tall hero images:

• Header: keep it to 80–120px tall where possible. Logo, maybe a three-link nav, done.
• Hero: if the headline and CTA sit in live text below the hero, a 600 x 400px landscape hero leaves room for both on the first screen. A square or portrait hero (600 x 600–750px) is more immersive on mobile but pushes the CTA below the fold, so put the offer inside the top half of the image as well.
• Long emails are fine. People scroll. They just need a reason to start, which is what the first screen is for.

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Mobile: why text in images shrinks

A 600px email on a phone is scaled to fit a screen roughly 360–430px wide. That means every image is displayed at roughly 60–70% of its design size. Text baked into an image shrinks with it:

Text size in the 600px design	Approximate size on a 390px-wide phone
16px	~10px (unreadable)
24px	~16px
32px	~21px
48px	~31px

So if a banner must contain text, design it at 28px or larger at 1x. Better still, keep headlines and CTAs as live text, which Klaviyo’s mobile settings can resize independently. Our email fonts guide covers live-text sizes.

Klaviyo’s editor also helps on mobile:

• Stacked columns: two- and three-column layouts stack into one column on mobile by default, so product images get more width.
• Full width on mobile: a toggle stretches an image edge to edge on phones.
• Display options: any block can be shown on mobile only, desktop only, or both. This is how you ship a portrait hero to phones and a landscape hero to desktop in the same email.

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Retina, Outlook and the width attribute

High-resolution screens (every modern iPhone, most Android phones, most laptops) show a 1x image slightly blurred. Exporting at 2x and displaying at half size fixes that. Two things to get right:

1. Always set a display width. In Klaviyo, set the image block width. In hand-coded HTML, include a width attribute on the <img> tag. Desktop Outlook for Windows ignores CSS widths in many cases and can show the image at its native 1200px, blowing out the layout. Klaviyo’s Outlook troubleshooting article lists “stretched or oversized” images as a known issue for exactly this reason.
2. Do not go beyond 2x. A 3x image adds weight and no visible benefit at email sizes.

Background images are another Outlook trap: Klaviyo notes that Outlook does not show background images in divs and table cells. Never put essential text or offers on a background image.

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File formats and file size

Format	Use it for	Notes
JPEG	Photography, lifestyle and product shots	Best compression for photos; 70–80% quality is usually indistinguishable
PNG	Logos, icons, flat graphics, text-heavy graphics	Crisp edges; heavier for photos
GIF	Simple animation	No automatic compression in Klaviyo; optimise first

Two numbers matter for load time:

• Per image: aim for under 200–400KB on heroes and under 100KB on product and column images.
• Total email: add up every image. An email with a 1MB hero and ten 200KB product images is 3MB on a mobile connection.

Image files are hosted externally, so they do not count towards Gmail’s clipping limit. Klaviyo’s help centre puts that limit at roughly 102KB of code on desktop and flags templates over 85KB as at risk. Long emails built from many blocks can hit it; heavy images cannot.

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Dark mode and your header

Logos are where dark mode breaks most visibly. A dark logo on a transparent PNG disappears when the inbox turns the background dark. Klaviyo’s dark mode guidance suggests two fixes: use image files that include their own background colour, or add a subtle light outline or glow around a dark logo on a transparent background so it stays visible either way.

Test your header in Apple Mail and Gmail in dark mode before you lock the template. You only have to solve it once.

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Designing banners in Canva or Figma

Whatever tool you use, set a custom canvas at 2x:

• Header: 1200 x 200px (displays at 600 x 100)
• Landscape hero: 1200 x 800px (displays at 600 x 400)
• Square hero: 1200 x 1200px (displays at 600 x 600)
• Two-column product tile: 540 x 540px

Export JPEG for photos and PNG for graphics, compress, then upload to Klaviyo and set the display width. Klaviyo’s Canva integration can export a whole Canva email design into Klaviyo as an HTML template, but per Klaviyo’s help centre it does not move standalone images between the two, so banners still need to be exported and uploaded.

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Common email dimension mistakes

• Uploading straight from the camera or photoshoot. 4000px, 6MB images. Klaviyo will scale them visually but your subscriber still downloads the weight.
• Whole-email images. One giant image slice looks right in the design tool and fails on image blocking, dark mode, accessibility and mobile text size.
• Headers that eat the first screen. Logo, nav, announcement bar, then a spacer. Four blocks before the offer.
• Forgetting the width attribute in custom HTML, so Outlook shows images at double size.
• Tiny text in product tiles. Prices and names in images become illegible when three columns stack or scale.

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The short version

Build at 600px wide. Export images at 2x (1200px) and display them at 600px. Keep headers 80–200px tall and heroes 300–600px tall, keep hero files under about 400KB, and keep headlines and CTAs in live text so they scale properly on phones. Set these once in a base template (our ecommerce email templates guide covers layouts by email type) and every campaign inherits them.

Want templates built to these specs and tested across Outlook, Gmail and dark mode? That is what our email design and copywriting service does for Klaviyo brands. Or start with a free Klaviyo audit, and we will flag what is slowing your emails down.