Email Signature Size Guide

Your email signature appears at the bottom of every message you send. For most professionals that is thousands of impressions a year, which makes it one of the most consistently viewed pieces of branding you own. Getting the dimensions right means it looks deliberate in Gmail, Outlook, Apple Mail, and on a phone, instead of overflowing the column or shrinking into illegibility. Use the checker above to test your own dimensions, and the sections below for the recommended sizes.

Recommended email signature dimensions in pixels

A standard professional signature should sit between 300 and 600 pixels wide, and between 90 and 200 pixels tall. Anything wider than 600 pixels risks horizontal scrolling in narrow reading panes. For individual elements: a profile photo works best at 80 to 100 pixels square, a company logo at 150 to 250 pixels wide and no more than 100 pixels tall, social icons at 24 to 32 pixels square with about 8 pixels of spacing, and a promotional banner at 500 to 600 pixels wide by 100 to 150 pixels tall. Always export images at two times those dimensions and then set the width and height attributes to the intended size, so the signature stays sharp on high-density displays.

Email signature size in centimetres and inches

Signature dimensions are often specified in centimetres, particularly for corporate templates that also get printed. Email images are measured at 96 pixels per inch, so one inch is 96 pixels and one centimetre is roughly 37.8 pixels. That makes a 500 pixel wide signature about 13.2 centimetres or 5.2 inches wide, and a 150 pixel tall block about 4 centimetres or 1.6 inches tall. A 100 pixel square profile photo is about 2.6 centimetres on each side. If your brand guidelines specify a logo in millimetres, multiply by 3.78 to get the pixel width you should export.

File size: what your signature adds to every email

Dimensions are only half the problem. Every image in your signature is downloaded on every message you send, and a signature carrying five unoptimized PNGs can add several hundred kilobytes to each one. Keep the total under 100 KB, and ideally under 50 KB. Use PNG only for logos and icons that need transparency, JPEG for photographs, and SVG only where you know the client supports it, which rules out most of Outlook. Never embed signature images as base64 inside the HTML: it inflates the message body by about a third and pushes you toward the Gmail clipping limit measured by our email size checker.

How signatures render across clients and on mobile

Outlook on Windows uses the Word rendering engine, which ignores CSS max-width and background images, so build the signature as a simple table and set explicit width and height attributes on every image. Gmail strips style blocks, so all styling has to be inline. Apple Mail and most mobile clients scale images down to fit, which is why exporting at two times size matters. Dark mode inverts backgrounds in several clients, so a black logo on transparency will disappear: give logos a solid background or supply a light variant. When you are ready to build one, our email signature generator produces the markup, and the Sequenzy email editor previews every block across clients before you send.