Free online image tool

Resize Image to 20KB

A 20KB cap usually comes from an application form that wants a scanned signature or a small photo and nothing bigger. The tool below already has 20KB selected. Upload your image and it finds the highest quality that fits, shrinking the dimensions only when it has to.

Free to use · No signup · No watermark

Drop your image here

or click to upload — JPG, PNG and WebP supported

JPEGPNGWebPup to 20MBpaste with Ctrl/Cmd+V

Your image is compressed in your browser and never uploaded.

Understand the limit

What a 20KB Limit Actually Allows

20KB is 20,480 bytes. A photo straight from a phone camera is often 2MB to 5MB, so it has to lose more than 99% of its data to get under this line.

That still leaves enough for the jobs a 20KB limit is written for. A signature is mostly blank paper with a few dark strokes, and blank paper compresses very well. A head-and-shoulders photo a few hundred pixels wide can also look fine at this size.

A large, detailed picture at full resolution will not fit. Upload a 4000-pixel photo and the tool will reduce its dimensions as well as its quality, because compression alone cannot close a gap that wide.

Target in bytes: 20,480
Usually for: Signatures, small form photos
Safest format: JPG

Use cases

When You Need an Image Under 20KB

Scanned signatures

Plenty of online application forms ask for a signature image with a very low ceiling. A clean scan or phone photo of your signature on white paper is the most common thing people bring to this page.

Small photos on the same form

Forms that ask for a signature often have a photo field with a similar limit. A tightly cropped head-and-shoulders photo can meet 20KB when its dimensions are modest.

Thumbnails and avatars

Some systems store a tiny preview image per record, such as a member avatar or a document thumbnail, and cap each one at a few kilobytes.

Older portals with strict checks

Upload systems built years ago often set tight limits and never raised them. They tend to reject a file that is even slightly over, so staying under matters more than getting close.

How it works

How to Compress an Image to 20KB

1
Crop before you start
Trim the empty paper around a signature, or the background around a face, in your phone's photo editor. Fewer pixels to store means sharper strokes at 20KB.
2
Upload the image
Drop the JPG, PNG or WebP file into the tool above, or tap the upload area to pick it from your phone. The target already reads 20KB.
3
Set JPEG if the form asks for JPG
Auto saves most images as JPEG, but it picks WebP for images with transparent areas. If the form only takes JPG, choose JPEG under Output format.
4
Resize, check and download
Select Resize Image and look at the Compare view. If the signature is readable and the photo still looks like you, download it.

Better results

Getting a Clean Result at 20KB

Photograph a signature on plain white paper in even daylight. Shadows and paper texture use up bytes the strokes need.
Sign with a dark pen. Thin, pale ink tends to fade into the background once compression smooths the image.
Upload the original photo, not a screenshot of it or a copy sent through a messaging app, which has usually been compressed once already.
If the form gives pixel dimensions as well as a file size, set those first with the Image Stretcher, then bring the result back here.
A small, clean image looks better than a large one full of compression blocks. If the tool reduced the dimensions, that was usually the better trade.

Frequently asked questions

How do I reduce a signature to 20KB?

Upload the signature image to the tool on this page. 20KB is already selected, so select Resize Image and download the result.

If your signature has a transparent background, choose JPEG as the output format. The transparent areas are filled with white, which is what most forms expect.

Why did my 20KB image come out smaller in pixels?

The original had more detail than 20KB can hold at full size. The tool lowers quality first and only reduces the width and height when that is not enough. The aspect ratio stays the same, and the result panel tells you by how much it was scaled.

Will the file be exactly 20KB?

It will be under 20KB, and usually close to it. Image encoders work from a quality setting rather than a byte count, so the tool searches for the highest quality that fits and stops there.

The form says 10KB to 20KB. Will the result meet the minimum?

Usually, because the tool aims for the largest file under your target rather than the smallest possible one. Check the final size in the result panel.

If it still comes out under 10KB, the image has very little detail to store, which happens with a small, plain signature. A larger or higher-resolution scan will produce a bigger file.

Can I compress a photo to 20KB on my phone?

Yes. The tool works in mobile browsers. Tap the upload area to choose a photo from your gallery, and the phone does the compression itself, so the image is not sent anywhere.

Not every form is this strict. If yours allows a little more, a larger target keeps more detail in the photo.