Email signature logo size: keep it small and sharp.

Recommended size at a glance

There is no official standard for signature logos, because every email program renders signatures differently. These ranges are widely used, practical starting points rather than rules:

The twice-the-size trick matters. A logo displayed at 200 pixels wide looks soft on a high-density phone screen if the file is also 200 pixels wide. Using a 400-pixel file and setting the display width to 200 gives a crisp image. Keep the file small by choosing a simple design.

Why small is better

• Phones. Many people read email on narrow screens, and a 600-pixel logo pushes layouts around or gets scaled down awkwardly.
• Weight. If the logo is embedded, it travels with every message. A 400 KB logo on every reply in a long thread makes mailboxes and attachments heavier than they need to be. See how to reduce image size for email.
• Professional look. A signature that is bigger than the message looks off.

PNG, JPG or WebP?

PNG is the usual pick for logos: crisp edges, flat colours and support for transparency, which is needed if the logo should sit on both light and dark mail themes. JPG suits a photo or a logo with gradients, but cannot be transparent and converting a transparent PNG to JPG gives a white background. WebP is often smaller but not all email apps display it reliably, so avoid it here. The trade-offs are covered in PNG vs JPG vs WebP and transparent PNGs explained.

Animated GIFs are possible but add weight and are shown inconsistently; most business signatures do not need them.

Step by step: prepare the logo

1. Start from the largest, cleanest version of your logo, ideally a PNG exported with a transparent background.
2. Crop empty margins with Crop image so the logo does not carry extra space.
3. Open Resize image and enter a maximum width of 400 to 600 pixels for a logo you will display at 200 to 300. The tool keeps proportions, never stretches and does not enlarge, so start from a file at least as big as the target.
4. Check the file size. If it is above about 50 KB, use Compress image with a target of 30 to 40 KB and look at edges and text in the comparison.
5. Check the dimensions and size together with Upload Check.

Remember that PNG is lossless, so you cannot lower a quality slider as you would with JPG. For a PNG, reducing pixels is the most effective lever. All of this happens in your browser; the logo is not uploaded.

Worked example

Say your logo is a 1,600 × 600 pixel transparent PNG of 180 KB. You want it displayed at 240 pixels wide.

1. Target file width: twice 240 is 480 pixels. Resize to a maximum width of 480, giving 480 × 180.
2. Pixels drop from 960,000 to 86,400, which is a ninety percent reduction, so the file will usually shrink a lot. Check the real figure shown after processing.
3. If it is still above 50 KB, compress toward 40 KB.
4. In your email program's signature editor set the image width to 240 pixels.

The numbers depend on how complex the logo is. A flat two-colour logo may land at 5 to 15 KB, while a logo with gradients and shadows can be larger.

Linked images vs embedded images

Email signatures can include an image in two ways. An embedded image travels with the message, so it displays offline but adds to each message's size. A linked image is loaded from a web address when the message is opened; it keeps messages light, but some email programs block remote images until the recipient allows them, so your logo may appear as a blank box or a missing-image icon. Neither is wrong. Many companies host the image on their own site. Whichever you choose, keep the file small, give the image alt text (the name of your company), and make sure your name and contact details are written as text, not baked into the picture.

Common mistakes

• Pasting a huge logo and shrinking it on screen. The file is still large.
• Making the file exactly as many pixels as it is displayed, which looks soft on phones.
• Putting phone numbers and links inside the image where they cannot be clicked or read by screen readers.
• Using a dark logo on a transparent background without testing dark mode.
• Choosing WebP when the recipient's email app may not show it.
• Sending a test only to yourself. Check how the signature looks on a phone and another email client.

Frequently asked questions

What size should an email signature logo be?

Commonly 150 to 300 pixels wide as displayed, with a source file about twice that so it stays sharp on high-density screens. Keep it under 50 KB.

What file size is best for a signature logo?

Under 50 KB is a sensible target, and many simple logos fit in 10 to 30 KB. Smaller files load faster and keep emails light.

Should I use PNG or JPG for an email signature logo?

PNG is usually best because it keeps edges crisp and supports transparency. Use JPG only for photo-like images. Avoid WebP because not all email apps show it.

Why does my logo look blurry in my email signature?

The file is probably too small for the size it is displayed at, or was enlarged. Start from a larger version, resize it to about twice the display width and set the display width in your signature editor.