A good email signature is about 600 pixels wide or less, with any photo or logo around 100 to 150 pixels on its longest side and saved as a small file. Those numbers keep it readable in the inbox, sharp on modern screens, and light enough to load instantly. Here is the detail.
Overall width
Email reading panes are narrow, and phones are narrower still. A signature that runs wider than about 600 pixels gets clipped or pushes the layout sideways. Staying within that width means the signature looks the same whether someone reads it on a laptop or a phone. The signature generator keeps the layout within sensible bounds for you.
Photo or logo dimensions
A headshot or logo of roughly 100 to 150 pixels on its longest edge sits nicely beside your text without dominating. For sharpness on high-resolution displays, export the file at about double those pixels but show it at the smaller size, so it stays crisp without looking oversized.
File size
Keep the image file small, a few tens of kilobytes is plenty for a signature graphic. A heavy image slows the message, can trigger image blocking, and weighs down every reply in a long thread. Compress the picture before you host it.
Keep the whole thing light
Beyond the image, the signature itself should stay compact: a few lines of text, one small graphic, a couple of links. A short signature reads better and travels better than a tall block. There is more on this in what makes a good email signature.
A quick checklist
- Overall width around 600 pixels or less.
- Photo or logo about 100 to 150 pixels on its longest side.
- Image file in the tens of kilobytes, not hundreds.
- Image hosted at a public web address so it loads for recipients.
Build a correctly sized signature with the email signature generator.
