How to get a photo under 20KB for an online form

Somewhere in the middle of an application form there is a line like Photograph: JPG only, 20KB to 50KB, 200×230 pixels. No explanation, no help, and an upload box that rejects your file without saying which of the three rules you broke. Meanwhile the photo on your phone is 4MB, which is two hundred times too large.

People need to do this all the time, and it is rarely explained well. So here is what those numbers mean, why your photo is so far off, and how to get inside the limits without ending up with something that looks like it was faxed.

The three limits are separate, and you can fail each one alone

Most rejected uploads come from mixing these up. They measure different things, and fixing one can break another.

• File size, in KB. How much disk space the file takes. This is what compression changes.
• Dimensions, in pixels. How many dots wide and tall the picture is. This is what resizing changes.
• Format. JPG, PNG, or sometimes PDF. This is what converting changes.

A photo can be exactly 200×230 pixels and still be 400KB. Another can be 15KB and still be rejected for being 3000 pixels wide. The limits do not depend on each other, and a form that only says “invalid photo” will not tell you which one it meant.

Why your phone photo is two hundred times too big

A modern phone camera takes pictures of roughly 4000×3000 pixels. That is twelve million pixels, and each one needs colour information. Even after JPEG compression, the file ends up somewhere between 2MB and 6MB.

The form wants 20KB. That is not a small change. It is asking for about half a per cent of what you have. You cannot get there by nudging a quality slider, and this is the point where most people give up and start pasting the photo into Paint.

You get there by doing two things, in the right order. The order makes a real difference.

Resize first, then compress

This is the main trick, and most guides get it backwards.

JPEG compression is lossy: it throws away detail the eye is unlikely to miss. If you compress a 4000-pixel-wide image down to 20KB, you are asking it to describe twelve million pixels with almost no information for each. So it throws away nearly everything, and you get the blocky, smeared result everyone knows as “a compressed photo”.

If you resize first, to the 200×230 the form asked for, you now have 46,000 pixels instead of twelve million. Describing those in 20KB is easy. The same 20KB spread over far fewer pixels lets each one keep its detail, and the photograph still looks like a photograph.

So: resize to the required dimensions, then compress to the required file size. If you do it the other way round, the compression is wasted on pixels you were about to throw away anyway.

Getting the dimensions right when the shapes disagree

Your photo is probably 4:3 or 3:4. The form probably wants something close to square, or 200×230, or 3.5×4.5cm. Those are different shapes, and you cannot fit one into the other without losing something.

You have two honest options and one bad one:

• Crop. Cut off the parts outside the required shape. You lose the edges, but nothing you keep is distorted. For a portrait photograph this is nearly always right, because the edges are just background.
• Add space. Put the whole photo inside the required shape and fill the rest with white. Nothing is lost or distorted, but the face ends up smaller in the frame, and some forms reject photos where the face is below a minimum size.
• Stretch. Force the picture into the new shape. Never do this. It makes faces look wider or longer, and it is the most common reason a photo is rejected as “not matching the applicant”.

Crop, in almost every case. A passport-style photo wants the head to fill most of the frame anyway, so the parts a crop removes are parts the form did not want.

Doing it here

Both steps run in your browser on this site. For this task that is more important than usual: an identity photograph is not a file to hand to an unknown server.

1. Resize the image to the dimensions the form asked for. If the form wants a size we do not have a page for, the general resizer takes any width and height.
2. Then compress it to 20KB, or 50KB, or whatever the form demanded. The tool works out the quality setting for you by trying values until one lands under the limit.

For an Indian exam form there is a shorter way. Each of the exam photo pages (IBPS, SSC, NEET, TNPSC and others) already knows that exam's pixel size and both ends of its KB range, and does the crop, the resize and the size in one step.

If the target really cannot be reached, the tool says so and tells you the smallest size it managed. It will not hand you something unreadable and let the form reject it.

The sizes forms usually ask for

Always use the number printed on the form you are filling. Departments change these, and no two agree. The table shows the usual shape of these requirements, so you know what to look for on the page.

What is being asked for	Typical file limit	Typical dimensions	What usually goes wrong
Passport-style photograph	20–100 KB	Around 200×230 to 350×350 pixels	The file fits but the shape does not, because the photo was cropped to a rectangle
Signature	10–50 KB	Wider than tall, often around 140×60	Photographed on lined paper, so the lines survive and the ink does not
Certificate or marksheet scan	200 KB–2 MB	No pixel rule, but it must stay readable	Compressed so hard the seal and the marks blur
Identity document	200–500 KB	No pixel rule	Sent as a photo when the form wanted a PDF

Five common questions, answered

• The form rejects my photo but the size is fine. It is also checking the pixel dimensions or the aspect ratio. Set both, not just the KB.
• Should I use JPG or PNG? JPG for a photograph, because at these sizes it keeps far more detail. PNG for a signature on white, where it can be smaller and stays crisp.
• Why is my signature file so large? It is a photograph of paper. Crop tight to the ink, convert to greyscale, and the size drops sharply.
• Can I just rename a .png to .jpg? No. The extension is only a label. The bytes inside are still PNG, and a strict upload check reads the bytes.
• My photo is under the limit but looks terrible. You compressed before resizing. Reduce the pixels first, then compress. The same file size will then carry far more visible detail.

When it still will not go small enough

Now and then a photo will not reach the target at any sensible quality. There are usually three possible reasons.

• It is still too large in pixels. Check the dimensions again. A 20KB target on a 1000-pixel-wide image is a fight. On a 200-pixel-wide one it is easy.
• It is a PNG. PNG is lossless, so it has no quality setting to trade away, and you cannot aim it at a file size at all. Photographs should be JPG. Convert it first with PNG to JPG.
• The background is busy. Compression works by finding areas that look alike. A plain wall behind you compresses to almost nothing; a bookshelf does not. This is part of why passport photos ask for a plain background. It is not only so your face can be seen.

Check it before you upload

Every operating system shows a file’s size and dimensions without extra software: right-click and choose Properties on Windows, or Get Info on a Mac. On a phone, the details or info panel in the gallery app shows both.

Thirty seconds of checking beats another rejected upload, especially on the government portals that make you fill in the whole form again after a failed submission.

A note on why this is so badly explained everywhere

The limits are not random. A department taking ten million applications with a 5MB photo each would need fifty terabytes of storage per intake, and a 200×230 thumbnail is all that ever gets printed on the card. The number is reasonable. What turns a two-minute job into an afternoon is that the form itself explains nothing.