How to reduce a photo to 20 KB

Every tool linked on this page runs in your browser, on a phone as well as a computer. The photo is not uploaded anywhere, and there is nothing to install.

Why a phone photo is a hundred times too big

A photo from a current phone has twelve million pixels or more and is a file of several megabytes. Twenty kilobytes is about a hundredth of that. No setting makes a full-size phone photo that small and leaves it looking like a photograph.

That is why a form with a 20 KB limit also asks for a small picture: a face a couple of hundred pixels wide, or a signature. Getting under the limit is therefore two jobs. First the picture has to become the size the form wants. Then what is left has to be compressed. People who skip the first job end up with a blurred, blocky face, because all of the saving has been forced out of the quality.

Step 1: read what the form asks for

Find the part of the notice or the instruction page that describes the uploads. It gives up to four things, and a file has to meet all of them.

• The format. Almost always JPG, also written JPEG. A PNG or a HEIC file is refused even at the right size.
• The dimensions. In pixels, such as 200 × 230, or in centimetres, sometimes with a DPI.
• The largest file size. The 20 KB in question.
• The smallest file size. Many forms set one, and a file below it is refused just as firmly.

The figures differ from form to form and from year to year. To give two that this site has read in the bodies' own instructions: the Staff Selection Commission's notices of 2025 and 2026 ask for a signature of about 6 by 2 cm between 10 and 20 KB, and the instructions for an online PAN application ask for a photograph of at most 20 KB scanned at 200 DPI. The guide to exam form sizes sets several of them side by side.

Step 2: crop and set the pixel size

Crop first, so that the picture has the shape the form wants, then resize it to the pixel size. Doing it in that order stops the face being stretched.

If the form gives pixels, use them as they are. If it gives centimetres and a DPI, the pixels are the centimetres divided by 2.54 and multiplied by the DPI: 3.5 cm at 200 DPI is 276 pixels. If it gives centimetres and no DPI, any sensible value will do, because the form can only check the file size; 200 is the usual scanner setting. The centimetre resizer does that sum and saves the DPI in the file.

For a plain crop and resize, the Image Cropper and the Image Resizer do the two steps. For a form this site has a page for, that page does both at once with the numbers filled in.

Step 3: compress to the limit

Now compress what is left. A JPG has a quality setting, and the file shrinks as the setting falls. Finding the highest setting that still fits is a matter of trying several, which is what Compress Image to 20KB does for you: it searches the quality for the best result under the limit, and scales the picture down only if quality alone cannot get there. If you resized properly in step 2, it will not need to.

What 20 KB can hold

These are the cases on the 20 KB tool's own page. They are a guide to what to expect, not a promise for your particular photo: a plain background compresses far better than a patterned one.

The pattern is plain. Up to about 300 pixels on the longer side, 20 KB is comfortable. At passport size it is tight. If the form wants a passport-size photo, its limit is more likely to be 50 KB, and that page is the one to use.

Signatures are a different case

A signature is the easy case for the maximum and the hard case for the minimum. Dark ink on white paper is mostly blank, and blank paper costs almost nothing to store, so a signature fits in 20 KB without effort. The trouble comes from the other end: a neat signature on clean paper can come out below a 10 KB minimum.

Three habits help. Sign in black ink on plain white paper. Photograph it in even light, near a window, without the phone's shadow across the page. And crop close, so that the signature fills most of the frame. A small mark in the middle of a large blank image is a reason for refusal in itself.

When a file is under the minimum, it can be brought up to it. The size increaser saves the picture at full quality and, if that is still short, adds filler data to the file. That adds bytes and no detail, which is all a minimum asks for. The Signature Resizer handles both ends of a range in one go.

Which kilobyte the form means

A kilobyte is 1,000 bytes to some programs and 1,024 to others, so "20 KB" is either 20,000 or 20,480 bytes, and forms do not say which they use. A file of 20,300 bytes passes one and fails the other.

The safe reading is the smaller one for a maximum and the larger one for a minimum. The tools on this site work that way: a limit of 20 KB is treated as 20,000 bytes, and a minimum of 10 KB as 10,240. Windows counts in units of 1,024, so a file of 20,000 bytes is shown there as 19.5 KB. That is correct and not a sign that anything went wrong.

Check the file before you upload

Look at three things: the extension is .jpg, the pixel size is the one the form gave, and the file size is inside the range. On a computer, the file's properties show all three. Each tool here also states the pixels and the size of the result beside the download button.

What no tool can check is the photograph itself. A form can refuse a correctly sized file because the photo is old, the background is wrong or the face is not clear, and those rules are in the notice too.