Signature Resize: Crop and Compress Your Signature to the Right KB
Signature resize in KB turns a photo of a signature into the KB range and pixel size a form asks for, such as 10–20 KB.
Crop to fill removes blank paper only. If a stroke would be cut, white edges are added instead.
Your files never leave your device. Compression runs entirely inside your browser using your phone or computer's own processor. Nothing is uploaded to a server, nothing is stored, and the page keeps working even if you go offline after it loads. Re-encoding a photo builds a new file from pixels, so camera metadata such as GPS is removed. Read the privacy policy.
How to resize a signature for an online form
- Choose a photo of the signature. Crop by dragging the frame, or press Auto-trim to cut the empty paper.
- Set a range such as 10–20 KB. Clean the background if the paper looks gray.
- Enter pixels, or switch to centimetres and a DPI. Download the JPG and check the byte count on the card.
Many application sites want both a small file and a tidy crop. A full desk in the photo wastes the KB budget. The output is always JPG. Transparent edges become white.
Getting a clean signature photo
Use plain white paper and a black or blue pen. Write in even indoor light, with the camera directly above the page so the lines stay straight. A hard shadow from the phone darkens one side and makes the cleaner treat the shadow as ink.
If the paper is still gray, raise the threshold until the background swatch in the preview goes white and the pen remains. Pure black and white is the smallest. Keeping the ink color looks closer to the pen and costs a few extra KB. Auto-trim then removes the margin so each side is only a small fraction of the width.
Pixels, centimetres and DPI explained
A file does not contain centimetres. It contains pixels. Centimetres only appear when you also choose a DPI, short for dots per inch. One inch is 2.54 centimetres, so the formula is:
pixels = round(centimetres ÷ 2.54 × DPI)
Worked example at the box’s starting value of 200 DPI, which is not a requirement from any form: 3.5 ÷ 2.54 × 200 = 275.6, which rounds to 276. 1.5 ÷ 2.54 × 200 = 118.1, which rounds to 118. So 3.5 cm × 1.5 cm becomes 276 × 118 pixels. If the form prints a pixel size, ignore centimetres and type the pixels. If it prints centimetres and a DPI, use those. If it prints neither, keep a width close to the crop.
Lock “exact pixel size” when the form will measure the dimensions. Turn it off only when hitting the KB range matters more than the exact frame. The tool will not pad a tiny signature with junk bytes to fake a larger file.
Your privacy
Your files never leave your device. Compression runs entirely inside your browser using your phone or computer's own processor. Nothing is uploaded to a server, nothing is stored, and the page keeps working even if you go offline after it loads. Re-encoding a photo builds a new file from pixels, so camera metadata such as GPS is removed. Read the privacy policy.
Frequently asked questions
What signature size do forms want in KB and pixels?
Use the KB range and the pixel or centimetre size printed on the form you are filling in. This page does not store portal rules; 3.5 cm by 1.5 cm at 200 DPI is 276 by 118 pixels, and a 10–20 KB strict range is 10,000–20,000 bytes.
Why does a form ask for a minimum KB as well as a maximum?
Some upload checks reject a file that is too small, because a tiny file is often a blank or a thumbnail. They also reject a file that is over the maximum.
Set both ends of the range, for example 10 KB to 20 KB. The tool aims for the highest quality that still fits under the maximum and, when it can, stays above the minimum.
If the signature is so simple that even the best quality is under the minimum, the page says so. It does not pad the file with junk.
What if the paper behind the signature looks gray?
Turn on Clean background. Pixels lighter than the threshold become pure white, and the pen stroke is darkened. You can keep the ink color, make it gray, or make it pure black and white.
Move the threshold if the pen starts to disappear or if the gray paper remains. A higher threshold treats more pixels as paper.
Auto-trim then cuts away the empty margin so the signature fills the frame. Take the photo on white paper in even light and you will need less cleaning.
Can I photograph the signature with my phone?
Yes. Use a black or blue pen on plain white paper. Hold the phone directly above the page so the signature is not skewed, and avoid a hard shadow from the phone.
Crop to the signature before you compress. A whole desk in the photo wastes the KB budget on things the form will not accept.
The page accepts a normal photo file. It does not open the camera by itself, so you can pick a picture you already took.
How do centimetres and pixels relate?
Pixels are the real size of the file. Centimetres only mean something when you also pick a DPI, which is dots per inch. The conversion is pixels = centimetres ÷ 2.54 × DPI, rounded to the nearest pixel.
At the box’s starting value of 200 DPI, 3.5 cm × 1.5 cm becomes 276 × 118 pixels. That DPI is only a starting number on this page. It is not a rule from any form.
If the form prints a pixel size, switch the unit to pixels and type that size. If it prints centimetres, use centimetres and the DPI the form names. When it names neither, keep the cropped photo’s own pixels.
Does the signature photo get uploaded?
No. Cropping, cleaning, and compression all run on your device. The download is a new JPG built in the browser.
Re-encoding removes camera metadata, including location. The original file on your phone is left untouched.
You can load the page, go offline, and still finish a signature you have already opened.