Compress image to a size in KB

Drop the image on the tool, pick the size in KB, and download. pdfly writes the image, measures the real file, and keeps the best version that is at or under your size. You do not have to guess a quality setting or try again and again until a form accepts the file.

1. Drop one JPG, PNG, or WebP on the tool, or browse for it. It can be up to 100 MB.
2. Check the format. It starts on the format your image already has; change it if the form asks for another.
3. Pick a size. 50 KB opens selected because many forms ask for it. Choose Custom for any other number.
4. Start. A short line tells you the new size and the picture's width and height in pixels.
5. Download the image and upload it to your form.

Exam, visa, job, and government forms often limit each file to a small size and refuse anything heavier, usually without saying by how much. A signature is commonly capped at 10 or 20 KB. A passport-style photo is often capped at 50 KB, sometimes 20 to 100 KB. Scanned certificates and ID cards tend to get 100 to 300 KB. Always use the number printed on the form, since it is the one that will be checked.

A photo from a phone is usually 2 to 5 MB, so getting it to 50 KB means a file about a hundred times smaller. That is possible, but not by quality alone: the picture also needs fewer pixels. pdfly does both, in that order, and stops at the first version that fits.

For JPG and WebP, pdfly looks for the highest quality whose file is still under your size, so an image with room to spare stays as clear as it can be. It never goes below a moderate quality, because past that point faces and text break into blocks. PNG has no quality setting, so pdfly keeps every color when the file fits and tries 256 colors when it does not; signatures and line drawings usually look the same either way.

When even the lowest quality is too big, the picture is made smaller, a step at a time, and the search runs again at each step. A smaller picture stays sharp; it just has fewer pixels. This is why a 12-megapixel photo can come back at a few hundred pixels wide for a 20 KB limit: that is what fits. If you need more detail, pick a larger size.

Forms sometimes give two limits: a file size, such as 50 KB, and a picture size, such as 200 by 230 pixels. They are different things. The file size is how much the file weighs; the pixel size is its width and height. This tool works to the file size and tells you the width and height it ended at, so you can compare them with the form.

If the form fixes the pixel size too, crop or resize the picture to those pixels first, with the photo editor on your phone or computer, then compress it here. A picture that is already small in pixels usually fits a KB limit at a high quality.

JPG is the safe choice for photos: every form and phone opens it, and it reaches small sizes well. PNG is lossless, so it suits signatures, stamps, and drawings with sharp edges, and it keeps a transparent background. WebP looks better than JPG at the same size and keeps transparency, but some older forms do not accept it. When you change a PNG with a clear background to JPG, the background turns white.

When the image is changed, its hidden details, such as the camera model, the date, and the location the phone saved, are left out of the new file. A photo the camera saved sideways is turned upright first, so it looks the same on the form as on your phone.

Some forms take documents only as PDF. If you have photos of the pages, turn JPG images into a PDF with a size limit for the whole file. If you already have a PDF that is too big, use the PDF compressor. And if the form wants images but you have a PDF, you can turn PDF pages into images under a size per image.

One image at a time: a JPG, PNG, or WebP up to 100 MB and 40 megapixels. The size can be anything from 8 KB to 100 MB. A side is never made shorter than 32 pixels, so a very long, thin picture may not reach a tiny size; pdfly then says how small it got. The upload and the result are deleted within 1 hour, and there is no account to create.