Email signature image size tool

Keep every image no taller than 100 pixels as it shows. Gmail’s help recommends signature images 70 to 100 pixels high and 300 to 400 wide, and gives 100 pixels high by 1,000 wide as the most it takes (Gmail Help). A logo taller than that starts to outweigh your name.

Email signature logo size. Set a wide logo by its width, 120 to 200 pixels, and a square mark by its height, 48 to 80. Trim the empty space around the logo first, or the margins count toward its size and the logo itself comes out small. The tool trims for you when it finds plain edges.

For comparison, the Templates in esigna’s gallery show a headshot between 42 and 132 pixels wide, most often 56 to 96, and a logo 80 to 120 pixels wide.

Aim for a signature about 300 to 450 pixels wide. Phones show an email at roughly 360 to 430 pixels across, less the email app’s margins, so a signature in that range shows at full size on a phone and sits comfortably on a computer. Wider than about 600 pixels and it starts to look like a banner.

For height, the name, title and contact lines plus one image row usually come to 100 to 150 pixels. A headshot beside the text, at 64 to 100 pixels, sets the height on its own; a logo under the text adds its own height, which is one more reason to keep it short.

Phones, and many laptops and monitors, fit two or more screen pixels into the space of one. An image saved at exactly 100 pixels wide and shown at 100 is stretched over 200 or 300 screen pixels there, and looks soft. Saved at 200 and shown at 100, it is sharp on every screen.

The catch is the email app has to be told to show the image at half its size. A signature made in esigna’s Editor, or any HTML signature with the width set, does that. Gmail’s own signature box doesn’t: it shows an uploaded image at the size of the file. If you upload there, either download the 1x file from the tool, or select the image after uploading and choose Small, Medium or Large, as Gmail’s help describes.

Going beyond twice the size adds weight without adding sharpness, and the tool never makes a file larger than your original. If your image is smaller than 2x needs, it says so.

Gmail.In the signature box, insert an image by uploading it, choosing it from Google Drive, or giving its web address. Gmail counts an image toward the signature’s 10,000 character limit, and its help suggests making the image smaller if you get an error (Gmail Help). Steps: add a signature in Gmail.

Outlook. In classic Outlook for Windows, insert the image in the signature editor, then right-click it, choose Picture, and set the size on the Size tab with Lock aspect ratio checked (Microsoft Support). Steps: add a signature in Outlook.

Apple Mail. On a Mac, choose Mail, Settings, then Signatures, and add an image by dragging it into the preview on the right (Apple Support). Steps: add a signature in Apple Mail.

The usual way to round a photo in an email is CSS border radius. Gmail and Apple Mail follow it; Outlook for Windows, up to its 2019 version, does not, and shows the square photo underneath (Can I email).

Choose Round or Rounded in the tool and the corners are cut into the picture itself, as a PNG with see through corners. Nothing is left for an email app to get wrong, so the photo is the same shape everywhere.

A logo or headshot at signature size should weigh tens of kilobytes, not hundreds. A photo straight off a phone is often 3 to 5 megabytes and thousands of pixels across; shrunk to 176 pixels square it comes to about 10 KB as a square JPEG, or about 55 KB as a round PNG.

The tool picks the format for you. Logos, and photos with round or rounded corners, are saved as PNG, which keeps edges crisp and corners see through. A square photo is saved as JPEG, which is several times smaller for photographs. The weight shows before you download.