About this tool
Application forms ask for a signature as an image file, and they usually ask for it twice over: a fixed pixel size, and a maximum file size in kilobytes. Meeting one and missing the other gets the upload rejected. This tool treats the pixel size as fixed and works on the file size around it, because that is the order the checks actually run in on the other end.
The two numbers in the boxes when the page loads are 140 × 60 px and 20 KB. They are there so you have something concrete to edit, not because they are right for you. Nobody here has verified your form’s rules and nobody can — different portals want different things and the same portal changes its mind between years. The instructions page of the site you are applying on is the only source worth trusting, so open it in another tab and copy the numbers across.
If your KB limit cannot be reached at the pixel size you asked for, the tool stops and says so instead of finding a way. That is a deliberate choice. The easy alternative is to shrink the image until the file gets small enough, which produces a download that looks fine and fails a dimension check weeks later, when there is nothing you can do about it. An error on this page costs you thirty seconds; the other kind of failure costs you the application.
All of this happens in your browser. The signature is read into memory on your own device, redrawn on a canvas, and encoded back to a JPEG by your own processor. No copy of it is sent anywhere, which is worth something for a file that is, after all, your signature.
How to use this tool
- Choose your signature image. A photo or scan of your signature on plain paper works. JPG, PNG and WebP are accepted, up to 50 MB.
- Enter the width and height in pixels. The boxes start at 140 × 60 px. That is an example to get you moving, not a rule — replace both numbers with whatever the form you are filling actually asks for.
- Set the maximum JPEG size in KB. It starts at 20 KB. The result lands at or below the number you type, not at an exact byte count.
- Choose how it should fit. “Fit with white padding” keeps the whole signature inside the box and fills the leftover space with white. “Fill and crop from the centre” stretches the picture out to the edges and cuts off whatever hangs over.
- Run it and check the result. You get the before and after file size, the pixel dimensions of the output, and a preview. Save it once it looks right.
What this tool does not do
- It does not know any portal's requirements and cannot confirm that a file will be accepted. Check the instructions on the site you are applying to.
- It does not remove the background, darken faint ink, or trim the paper around your signature. Crop first if you need that.
- The output is always JPEG. Transparency is filled with white.
- It cannot add detail that is not in your photo. Blowing up a small, blurry scan gives you a larger blurry scan.
- It will not land on an exact byte count — only at or below your KB limit.
Common questions
What dimensions and file size should I use?
We cannot tell you, and any site that gives you a confident number for your particular form is guessing. Open the portal you are applying on, find its instructions page, and read the current numbers there. Portals change these without announcing it. The 140 × 60 px and 20 KB in the boxes are a starting point so the form is not empty, nothing more.
I got “That size limit cannot be met at these dimensions.” What now?
It means even at the lowest JPEG quality the picture will not fit under your KB limit at the exact pixel size you asked for. The tool stops there on purpose. It could have quietly shrunk the image to make the number work, but then you would have downloaded a file with the wrong dimensions and found out at the counter instead of here. Either raise the KB limit or reduce the pixel width and height — whichever your form allows.
Does it change the width and height I typed?
No. The output is exactly the pixel size in the two boxes, every time. Quality is what gets sacrificed to reach the file size, never the dimensions.
My signature came out on a white block instead of a transparent background.
The output is always JPEG, and JPEG has no transparency. A PNG with a see-through background is flattened onto white. For a signature going into an upload box that is usually what you want anyway, since the form will show it on white.
The signature looks faint or grey after resizing.
That comes from the photo, not the resize. A phone picture of paper picks up shadow and the paper tint. Photograph it again in flat, even light, or crop tightly around the ink first with the image cropper, then run this.
Can I use this for a photo instead of a signature?
Yes — the tool does not care what the picture is. If you want the photo dimensions pre-filled instead, the photo and signature presets tool has both as selectable starting points.