Email signature blurry? The usual reason is simple: the logo file has the same pixel width as the space it fills on screen, and high-resolution screens need more pixels than that. Save the file at twice the width you display, insert it at the smaller size, and the soft edges go away. The explanation comes from Mozilla’s responsive images guide, and the app steps from Google and Microsoft, all read in October 2026.
Email signature blurry: the quick fix
- Find the size the logo is shown at, in pixels wide.
- Export a new file at twice that width, from the original artwork.
- Insert it and set the displayed width back to the smaller number.
- Use PNG for logos and JPEG for photos.
- Never enlarge a small file to fix softness.
Why the email signature blurry problem happens
A picture file has a fixed number of pixels. Mozilla’s guide says a raster image is a set number wide and a set number tall, and that a small one starts to look grainy when shown larger than its original size. It adds that some devices have high-resolution screens that need larger images than you might expect, and it describes screens with two device pixels for each CSS pixel, or more. A 160 pixel logo shown at 160 pixels wide on such a screen is stretched across twice as many dots, and it looks soft.
That one idea explains most cases of an email signature blurry only on newer screens. The table lists the causes in the order we would check them.
| Cause | What you see | Fix |
|---|---|---|
| File saved at the displayed width | Soft edges on a phone or laptop with a sharp screen, fine on an old monitor | Export at twice the displayed width |
| A small file enlarged in the editor | Pixel blocks and jagged curves | Find the original artwork and export again |
| Lossy format for a logo | Fuzzy halos around letters | Use PNG instead of JPEG |
| Very few colours | Banding or rough gradients | Avoid GIF for anything but simple art |
| Aspect ratio not locked | Stretched, so soft in one direction | Reset and lock the ratio |
Email signature blurry? The 2x method with exact pixel pairs
To fix an email signature blurry at its current size, pick the displayed size first. Then multiply by two.
| Item | Displayed size | File to export |
|---|---|---|
| Wide wordmark | 120 by 40 pixels | 240 by 80 pixels |
| Standard logo | 160 by 50 pixels | 320 by 100 pixels |
| Large logo | 200 by 66 pixels | 400 by 132 pixels |
| Headshot | 100 by 100 pixels | 200 by 200 pixels |
| Social icon | 24 by 24 pixels | 48 by 48 pixels |
| Banner | 300 by 75 pixels | 600 by 150 pixels |
Three notes on that table. The displayed sizes are our suggestions, not vendor rules. The factor of two is ours too, chosen because it covers the two device pixels per CSS pixel case that Mozilla describes. And some phones go higher than two, which is why a flat-colour PNG is the right place to spend extra pixels: it stays small even at three times.
Export from the original, not from a screenshot
Start from the largest source you have: the vector logo from your designer, a high-resolution export, or the original photo. A screenshot of a logo on a website is already low-resolution, and you cannot add detail back.
Set the displayed size once
After inserting the 2x file you must tell the app to show it at the smaller size, otherwise it appears twice as big. In classic Outlook, Microsoft’s steps say to right-click the picture and resize it with the aspect ratio locked. Gmail’s editor has its own sizing options, and our Gmail image guide lists them. Keep the ratio locked in both. The logo guide has click paths for each app.
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Example only: a logo and social icons in a drawn signature, the kind of images the 2x rule applies to. The company and person are made up.
One caveat on Gmail. Google’s troubleshooting page recommends signature images 70 to 100 pixels high by 300 to 400 wide, with a maximum of 100 by 1,000, but it does not say whether those numbers mean the file’s pixels or the displayed size. We have not tested which, so check after saving: if your 2x file appears larger than you set, resize it down in the editor and look again.
Which formats keep an email signature from going blurry
Mozilla’s image type guide is clear on the main points.
- PNG for logos, diagrams and line art. The page says to prefer lossless encoding for those, because blurring and coloured fringes around text and sharp edges are very visible.
- JPEG for photographs. It is lossy and the guide says to avoid it for text and sharp edges.
- GIF is limited to a 256 colour palette, so for still images the guide says to prefer PNG.
- SVG is a vector format, scalable without loss, but the page is about browsers. It says nothing about mail apps, so we do not recommend it for signatures. Microsoft’s page on signature photos and links lists .bmp, .gif, .jpg and .png for Outlook.
For a blurry logo in an email signature, the practical choice is PNG, exported at twice the width. For a headshot, a JPEG at the same 2x rule works.
Check for a blurry email signature on real screens
Do not trust the editor preview. Test an email signature blurry or sharp the way a reader sees it.
- Send the signature to yourself and open it on a phone.
- Open it again on a laptop. A screen with a sharp display shows a problem sooner than an old monitor.
- Zoom in on the logo. Jagged edges mean the file is too small, fuzzy halos mean the wrong format.
- Compare two clients, since each rescales differently.
If the picture is sharp on screen but heavy, the guide to a signature that is too big covers the weight. If the logo disappears in dark mode instead of blurring, that is a different problem, covered in the dark mode guide.
When the email signature blurry fix does not work
- You doubled the file but not the displayed size. The logo now looks twice as big. Reset its width.
- You doubled both. The signature is still the same sharpness as before, only larger.
- The size did not stick. Insert the picture with the app’s image button, set the size, save, and look at the saved result rather than the preview.
- The reader’s app blocks the picture. Nothing is blurry, it is simply missing. See signature images that show as attachments and the guide to signature size.
If a team shares the logo, an email signature blurry on one machine usually means someone saved their own copy. emailfooter keeps one logo in the shared design, so every person pastes the same file. It does not push the signature to mailboxes, and each person still checks it on their own screen.
Frequently asked questions
Why is my email signature blurry?
The image file is probably the same width as the space it fills. That is the usual reason for an email signature blurry on a phone. Export it at twice the displayed width and set the display size back to the smaller number.
How do I fix a blurry logo in an email signature?
Get the original artwork, export a PNG at twice the width you plan to show, delete the old picture, insert the new one and lock the aspect ratio.
What size should a logo be so it is not pixelated?
Our suggestion: displayed at 160 by 50 pixels, saved at 320 by 100. Mozilla’s guide explains that high-resolution screens need more pixels than the displayed size.
Email signature blurry: is PNG or JPEG better?
For logos, PNG, because Mozilla’s guide recommends lossless formats for logos and line art. Use JPEG for photographs.
Keep reading
- How to add a logo to your email signature in any email app: How to add logo to email signature in Gmail, Outlook and Apple Mail from one prepared file, with the format, pixel size, hosting choice and fixes.
- 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 too big? Cut the pixels, the kilobytes and the lines: Email signature too big on screen or in file size? See target pixel and kilobyte values per element, the limits vendors publish, and a worked 80 percent cut.
- Email signature in dark mode: fix invisible logos and unreadable text: Email signature dark mode fixes: why logos vanish and text fades, how to repair both, and a test routine for Gmail, Outlook and Apple Mail.
Make every signature in your company match
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