Email Signature Size Guide: Ideal Dimensions for Logo, Photo & Banner

Get the dimensions wrong and your email signature looks either comically large or impossibly tiny. Worse, oversized images get blocked by email clients or push your actual message below the fold. Here are the exact numbers to aim for.

Quick Reference Table

Overall Signature Dimensions

The sweet spot is 600 pixels wide by 150 to 200 pixels tall. This fits comfortably in every major email client — Gmail, Outlook, Apple Mail, Thunderbird — without triggering horizontal scrollbars or clipping.

Why 600px? Most email clients render the message body at around 600-640 pixels wide. Go wider and your signature either gets cropped or forces the recipient to scroll horizontally. On mobile, the email client scales everything down to fit the screen, so a 600px signature adapts naturally.

Height is more flexible. Aim for under 200px to keep your signature compact. Anything taller starts to feel like an advertisement rather than a sign-off. Remember: people scroll past your signature to reach the previous message in a thread.

Logo Dimensions

Keep your logo under 400 pixels wide and the file under 150KB. Most signatures display logos at 150-250px wide, which looks proportional next to your contact details.

Use PNG for logos with transparency, or SVG if the email client supports it (most do not — stick with PNG for maximum compatibility). JPEG works for photographic logos but produces artifacts on sharp edges and text.

A common mistake: uploading a 2000px-wide logo and relying on HTML width attributes to shrink it. The image still downloads at full size, slowing down the email. Always resize the actual file to the display dimensions.

Profile Photo Dimensions

Use a 200 × 200 pixel square image, kept under 100KB. This renders crisply at the 80-100px display size most signatures use, while accounting for Retina and high-DPI screens that need 2x resolution.

Crop the photo tight — head and shoulders, centered. Avoid full-body shots or group photos. The image will display at roughly the size of a thumbnail; fine details vanish. Use JPEG at 80% quality for the best size-to-quality ratio.

Round or square? Both work. Round photos feel more modern and personal. Square photos feel more corporate. Pick what matches your brand.

Banner / CTA Image Dimensions

If you include a promotional banner (for an event, product launch, or seasonal campaign), use 1200 × 300 pixels at under 200KB. The 4:1 aspect ratio displays well across devices without dominating the signature.

Banners are optional, and not every signature needs one. But when used strategically — say, to promote a webinar or a new feature — they can drive significant clicks. Make sure the banner links somewhere useful and track those clicks to measure ROI.

Social Media Icon Dimensions

Social icons should be 20 to 24 pixels square. This size is large enough to tap on mobile but small enough to sit in a neat row without overwhelming your contact info.

Use consistent icon styles — all filled, all outlined, or all monochrome. Mixing styles (a colorful LinkedIn icon next to a monochrome Twitter icon) looks sloppy. Keep each icon under 5KB; since you might have 4-6 icons, the total should stay minimal.

Image Format Cheat Sheet

• PNG — Best for logos and icons (sharp edges, transparency support)
• JPEG — Best for photos (smaller file size for photographic content)
• GIF — Only if you need animation (not recommended for signatures)
• SVG — Not supported by most email clients. Avoid.
• WebP / AVIF — Not supported in email. Stick to PNG and JPEG.

Let EmailSign Handle the Math

Remembering pixel dimensions and file size limits is nobody's idea of fun. The EmailSign builder automatically crops, resizes, and compresses every image you upload — logo, photo, banner, icons — to the optimal dimensions for email. Upload whatever you have; the tool handles the rest.