An email signature too big can mean three different things, and each has a different fix: the pictures are shown too large, the files behind them are too heavy, or there are simply too many lines. Work out which one you have, then use the target values below. The limits we quote come from Google’s signature page, its troubleshooting page and Google’s Workspace help for admin signatures, read in October 2026. Where no vendor publishes a number, we say the figure is our own rule of thumb.
Email signature too big: first find which size
- Too wide or tall on screen: the pictures are displayed too large. Set smaller display sizes.
- Too heavy: the files are oversized. Export small, then compress.
- Too long: too many lines. Cut the repeated contact details and the legal text.
- Gmail will not save it: the 10,000 character limit counts images, so shrink the picture first.
Email signature too big: three kinds of big
| Kind of “too big” | What you notice | Measured in | Fix |
|---|---|---|---|
| Display size | The logo or photo dominates the message | Pixels as shown | Set a smaller width, lock the aspect ratio |
| File weight | Messages get heavy, Gmail refuses to save | Kilobytes and characters | Export at the right pixel size, compress |
| Length | The signature is longer than the message | Lines | Remove or merge lines |
Shrinking a picture in the editor only changes how it is shown. The file stays as heavy as before. To make the message lighter, replace the file.
What the vendors publish
Fewer numbers exist than you might expect.
- Gmail, pixels. Google’s troubleshooting page recommends a signature image of 70 to 100 pixels high by 300 to 400 pixels wide, with a maximum of 100 high by 1,000 wide.
- Gmail, characters. A signature holds up to 10,000 characters, and images count toward the limit. If you get an error, Google says to resize the image.
- Google Workspace admin footer. The admin signature page gives the same image dimensions.
- Outlook. Microsoft’s signature page does not state a size or character limit, so any number for Outlook is a rule of thumb.
Everything else here, kilobytes included, is ours. It is an estimate for sensible results, not a rule any mail app enforces.
Email signature too big: target values for each element
| Element | Shown size | Saved file | Weight to aim for |
|---|---|---|---|
| Logo | 120 to 200 pixels wide | Twice the shown width | Under about 30 KB |
| Headshot | 80 to 120 pixels square | Twice that, so 160 to 240 | Under about 40 KB |
| Social icons | 20 to 24 pixels square | 40 to 48 pixels | A few KB each |
| Banner (optional) | 300 to 500 pixels wide | Twice the width | Under about 60 KB |
| Text | One line per fact | n/a | About 5 to 7 lines in all |
The “twice” rule is explained in the blurry logo guide. MDN’s page on responsive images describes why: high-resolution screens show more device pixels for each CSS pixel, so an image saved at the shown size looks soft. That is the reason a small file is not the same as a tiny file. Make it small, but not smaller than twice the shown size.
For the display sizes in more detail, see the broader signature size guide.
A worked example: an 80 percent cut
The numbers below are invented to show the method. Your own files will differ, so measure them with your computer’s file information window.
| Item | Before | After | Saving |
|---|---|---|---|
| Logo | 1600 by 540 px file, 240 KB, shown 400 wide | 400 by 135 px file, 25 KB, shown 200 wide | 215 KB |
| Headshot | 1000 by 1000 px JPEG, 210 KB, shown 150 | 300 by 300 px JPEG, 40 KB, shown 150 | 170 KB |
| Four social icons | 256 px, 12 KB each (48 KB) | 48 px, 2 KB each (8 KB) | 40 KB |
| Banner | 1200 by 300 px PNG, 140 KB, shown 600 | 600 by 150 px PNG, 55 KB, shown 300 | 85 KB |
| Total | 638 KB | 128 KB | 510 KB (about 80 percent) |
The four items add up to 240 + 210 + 48 + 140 = 638 KB before and 25 + 40 + 8 + 55 = 128 KB after, a cut of 510 KB. The shown sizes shrank too: the logo went from 400 to 200 pixels wide and the banner from 600 to 300, so the signature is also much shorter on screen. If your email signature is too big on screen only, the display sizes are the part to change.
Step by step: fix an email signature too big for the message
- List every picture in the signature, with the pixel size it is shown at.
- Re-export each file at twice the shown size, as PNG for flat logos and JPEG for photos.
- Compress the exported file with the compression option in your image editor.
- Replace, don’t resize. Delete the old picture in the signature editor and insert the new file. In classic Outlook, Microsoft’s steps say to right-click the picture to resize it with the aspect ratio locked.
- Drop what does not earn its place. A banner and four icons rarely pay for their weight.
- Cut lines. Keep one phone number, one web address, no repeated email address.
- Move the legal text to a smaller font, or to an admin footer, as the disclaimer guide describes.
Vertical gaps can make a signature feel big even when the pictures are small. The line spacing guide covers the Outlook side of that.
Gmail says the email signature is too big
If Gmail rejects the signature on save, the 10,000 character limit is the one in play, and Google says images count toward it. Google’s advice is to resize the image, so replace the picture with a smaller file and save again. That is the quickest answer to an email signature too big for Gmail. If you see stray characters instead, Google’s troubleshooting page says to use Remove formatting.
Check the result as the reader sees it
Open your test message on a phone first. A phone screen is the narrowest place your signature will appear, so it shows an email signature too big faster than a laptop does. Look for three things: the logo should sit above the fold of the signature rather than fill the screen, no line should wrap awkwardly, and the signature should be shorter than the message above it. Then send the same test to another provider, and compare. If one app shows it larger than another, check that the picture sizes were set as widths and not left at their original size.
A signature that stays small
A compact layout keeps the whole thing to a few lines. This one is drawn by emailfooter, with made-up details:
|
Short lines, no photo, one number. The school and teacher are made up.
For more on keeping things light, read about the simple email signature. If you manage a team, emailfooter fixes the logo size once in the shared design, so nobody ends up with an email signature too big for their screen. Each person still pastes their own copy, and the tool is English-only for now.
Frequently asked questions
Why is my email signature too big?
Usually a picture is displayed too wide, or the file behind it is heavy. Check the shown size first, then the file weight.
How do I make my email signature smaller?
Replace each picture with a file saved at twice its shown size, compress it, and cut repeated lines. Resizing in the editor alone does not reduce the file.
What is the maximum image size for a Gmail signature?
Google’s troubleshooting page gives a maximum of 100 pixels high by 1,000 wide, and recommends 70 to 100 high by 300 to 400 wide.
Why will Gmail not save my signature when it is too large?
A signature holds up to 10,000 characters, and the image counts toward that. Google says to resize the image.
Keep reading
- Email signature size: width, image size and character limits: What is the best email signature size? Recommended width, logo dimensions, image file weight and the character limits in Gmail, so your signature looks right.
- Email signature blurry? The 2x export method and the pixel pairs to use: Email signature blurry or a pixelated logo? See the causes in one table, exact display versus file pixel pairs, and which image formats stay sharp.
- Simple email signature: 10 minimal examples that still look professional: A simple email signature is read before it is noticed. Ten minimal examples from two lines to six, as plain text you can paste, and three drawn in rich text.
Make every signature in your company match
emailfooter is a free WordPress plugin. You design the signature once, and each person adds their own details and installs it in their mail app. Prefer not to run a website? emailfooter Managed is the same software, hosted for you.