What size should an email signature image be?
Logos and headshots in email signatures often arrive huge, blurry or blocked. The pixel sizes and file sizes that work in Gmail and Outlook, and how to make them.
Published
Tools for this job: Resize Image · Compress Image · Circle Crop Image
An email signature image is seen thousands of times, often on a phone, often next to text that is only 14 pixels high. A 3,000-pixel logo pasted straight from the brand folder either fills the screen or gets squashed into a blurry stamp. A little preparation makes it look sharp everywhere.
Sizes that work
| Image | Shown at | Make it |
|---|---|---|
| Wide logo | 150–250 px wide | 300–500 px wide |
| Square logo or icon | 60–100 px | 120–200 px |
| Headshot | 80–120 px | 160–240 px |
| Banner below signature | up to 600 px wide | up to 1200 px wide |
The “make it” column is twice the display size. Phones and most modern laptops have high-density screens that use two physical pixels for every pixel of layout, so an image made at double size stays crisp. Going beyond double adds weight without any visible gain.
Keep the file small
Every email you send carries the signature, and every reply can carry it again. Aim for tens of kilobytes, not hundreds. A logo of 300 × 100 pixels should be well under 30 KB; a headshot of 200 × 200 pixels well under 40 KB. Large signature images also make some mail programs show them as attachments, which looks messy in the recipient's inbox.
Prepare the image step by step
- Resize to the “make it” width in Resize Image, with the aspect ratio locked.
- For a round headshot, cut it out with Circle Crop Image, which leaves the corners transparent so it sits on any background.
- Shrink the file in Compress Image. Photos compress best as JPG; logos with flat colours or transparency should stay PNG.
- Upload the image into your mail program's signature editor and set its display size there.
Why images go missing
- Blocked by default. Some mail programs, especially in business settings, do not load images until the reader allows them. Put your name, title and phone number in text, never only inside an image.
- Pasted rather than hosted. Gmail signatures need the image added through its image button, either from a web address or Google Drive. Pasting from a document often fails.
- Dark mode. A logo with a white rectangle behind it looks like a sticker on a dark background. Use a PNG with a transparent background, and check the logo still reads on dark grey.
Keep it modest
One image is plenty: either a logo or a headshot, rarely both, and only occasionally a banner for a current event. Social icons are optional; if you add them, keep them to about 20 pixels displayed and use the same style for all of them. A signature that is taller than the message it ends looks like an advertisement.
For the reasoning behind JPG versus PNG for logos and photos, see JPG vs PNG vs WebP. If your round headshot came out with a white square around it, the guide to making a round profile picture explains why.