Compress Image to 20 KB
Shrink a signature or a small photo under 20 KB for an application form, and see how far its pixel size has to drop, in your browser with no upload.
How to compress a signature or photo to 20 KB
- Crop the signature or photo tight first. At 20 KB, empty margins use up space you need.
- Drop the file on the box above. The target is already 20 KB.
- Press Compress image and read the dimensions in the result. For every photo I tried they fell.
- Download it and check it at the size the form will show it, not zoomed in.
Where 20 KB comes from
A 20 KB limit usually sits next to a signature field or a small passport-style photo box on an application form. At that size the form will only ever show a thumbnail, so the real question is how small your picture has to get.
I ran my three test photos, published on this site at 1,200 pixels on the long side, through this page at 20 KB. At 100 or 200 KB they kept their size; here none of them could. The red bicycle from Metelkova came out at 373 × 249 px. That is the thing to know about 20 KB: the pixel count drops as much as the quality does.
How small 20 KB makes a photo
| Photo | Original | At 20 KB |
|---|---|---|
| Lake Jasna, June 2019 | 960 × 1200 px, 415.0 KB | 420 × 525 px, 20.0 KB, quality 41% |
| Clay figure, Metelkova, March 2023 | 1200 × 800 px, 403.6 KB | 484 × 323 px, 19.9 KB, quality 41% |
| Red bicycle, Metelkova, March 2023 | 1200 × 800 px, 701.7 KB | 373 × 249 px, 20.0 KB, quality 49% |
The quality stayed above the 40% floor, between 41% and 49%. The tool would rather shrink a photo than make it blocky, so at this target you get a small, clean picture instead of a large, broken one.
Signatures and logos
I have no signature scan I would publish, so the nearest test I have is a logo: a 640 × 320 px PNG test file, a blue circle, a letter and a word of dark text on a transparent background, 31.5 KB. It kept its full size and came out at 14.3 KB as WebP at 92%, because the tool keeps transparency. Flat areas of one colour cost almost nothing, and a signature on white paper is mostly that.
Watch the format. If the signature field accepts JPG only, a WebP will be refused. Turn a transparent PNG into a JPG with a white background on PNG to JPG first; my logo became an 11.5 KB JPEG there.
Resize by hand, but far enough
Resizing first helps at 20 KB only if you go small enough. At 400 pixels wide the bicycle fitted at 400 × 267 px but only at 40%, worse than what the tool chose by itself. At 300 pixels it reached 72%. Lake Jasna at 400 pixels tall kept 320 × 400 px at 71%, and the clay figure at 400 pixels wide got 64%.
The tool does not go below 200 pixels on the long side or 40% quality. At 10 KB the bicycle still fitted, at 264 × 176 px and 47%. At 5 KB it did not: even at 200 × 133 px and the lowest quality the file was 5.6 KB, and the tool said so instead of handing me something unusable.
Text goes less far than it seems. My 2200 × 1400 px screenshot test file reached 20 KB at 676 × 430 px and 51%, and its smallest lines were at the edge of legible. A document that must be read needs a bigger limit, or a crop to the one line that matters.
Tips for signatures and small forms
- Sign with a dark pen on plain white paper. Pencil and lined paper both add detail the file has to store and read worse when small.
- Crop right up to the ink. A signature with wide margins spends its 20 KB on blank paper.
- Scan or photograph in even light, without the shadow of your phone across the page.
- If the form counts 1 KB as 1,000 bytes, enter 19 here, which is 19,456 bytes.
- Judge the result at the size the form shows it. At 20 KB the picture is meant to be small.
Privacy
Your image never leaves your device. Compression happens entirely in your browser, so nothing is uploaded or stored, and you do not need an account.
Frequently asked questions
What is the size of a 20 KB photo in pixels?
From my 1,200-pixel photos, between 373 × 249 and 484 × 323 px for landscape frames, and 420 × 525 px for an upright one. A smooth photo keeps more pixels than a busy one. Resize to the form's own size if it gives one.
What size should a signature be at 20 KB?
Use the pixel size the form asks for. If it gives none, a signature cropped to the ink on a white background should fit easily, because plain areas take almost no space: my 640 × 320 px test logo needed only 14.3 KB.
How do I turn a 20 KB signature into a 50 KB one?
Do not enlarge the 20 KB file; the detail it lost does not come back. Start again from your original scan and enter 50 as the target, or open the 50 KB page. The result will be sharper than the 20 KB file.
Can I compress an image to 20 KB without losing quality?
Not a normal photo. My three photos all lost pixels and fell to between 41% and 49% quality. A plain image such as a signature or a simple logo loses far less; my test logo kept its full size at 92%.
Related tools and guides
- Image Compressor: Reduce JPEG, PNG and WebP file sizes while keeping quality high.
- Compress Image to 100 KB: Fit a JPEG, PNG or WebP photo under 100 KB at the highest quality that fits, right in your browser and without uploading it.
- Compress Image to 1 MB: Fit a full-screen photo under 1 MB for email or an upload form while its quality stays high, compressed in your browser without uploading it.
- Compress Image to 200 KB: Bring a photo under 200 KB for a job or visa application while it keeps its full size, compressed in your browser and never uploaded.
- Compress Image to 50 KB: Get a photo or scan under 50 KB for an ID card or exam registration, and see the size and quality it keeps, in your browser with no upload.
- Image Resizer: Resize images by pixels, percentage or longest side.
- Convert PNG to JPG: Turn a PNG into a JPG for a form, an email or a site that will not take PNG. Transparent areas become white, all in your browser.
- How I Edited a Metelkova Graffiti Photo in Lightroom: Another photo from the place where I found the red bicycle.
- I Built the Tools I Kept Looking For as a Photographer: Why your signature never leaves your browser on these pages.