How to make a photo smaller in KB without it looking bad

A phone photo straight from the camera is usually a few megabytes. An online form asks for under 100 KB. That's a reduction of thirty or forty times, and if you do it the wrong way the picture turns into a smudge of blocks.

Done the right way, most people can't tell the difference at the size the photo will actually be seen. It comes down to two settings that people tend to mix up.

Pixels and quality are different things

Pixels are how many dots make up the picture, for example 4000 × 3000. Quality is how carefully those dots are stored. A JPG at quality 90 keeps fine detail; at 40 it throws a lot away and shows blocky patches around edges.

The size in KB depends on both, and pixels matter far more. Halving the width and height leaves a quarter of the pixels, and the file shrinks roughly in proportion, with no visible damage if the photo is shown small anyway. So the rule is simple:

1. First reduce the pixels to what the photo really needs.
2. Then lower the quality only as far as necessary to hit the limit.

A form photo displayed at 200 pixels wide gains nothing from being 4000 pixels wide. A photo for a website rarely needs more than 1920 pixels across.

JPG, PNG or WebP?

• JPG is right for photos and accepted almost everywhere. It's the safe choice for forms and email.
• PNG stores every pixel exactly. That's ideal for screenshots and logos, but a photo saved as PNG stays huge. If a PNG photo won't shrink, convert it to JPG.
• WebP gives the smallest files for the same look, and every modern browser shows it. Use it for websites; many older forms don't accept it.

Hitting an exact limit

Trial and error with a quality slider gets tedious. A target-size setting does the search for you: give it 100 KB and it finds the highest quality that fits, and only reduces the pixels if quality alone can't get there.

Some practical points for forms:

• Use the largest size you're allowed. If the limit is 20–50 KB, aim near 50, not 20. There's no prize for being far below.
• Check the pixel size too. Forms often want exact dimensions, such as 300 × 300 pixels, as well as a KB limit. Get the dimensions right first.
• Crop before you compress. Every pixel of background you crop away is space the important part can use.
• Don't compress the same file twice. Each round of JPG compression adds damage. Go back to the original whenever you need a new size.

Signatures need different treatment

A signature is dark lines on white, not a photo. Sign with a dark pen on clean white paper, photograph it in daylight, crop tightly around the signature, and make the background pure white. A clean signature compresses to a few KB and stays sharp, while a grey, shadowy one balloons and looks smudged.

A bonus: location data

Phone photos often contain hidden details, including the GPS position where they were taken. Sending a photo from home can share your address with whoever receives it. Re-saving a photo through a compressor that writes a fresh file, like ours, leaves that information behind.

When it really won't fit

If a photo still looks bad at the size you need, the limit is probably meant for a smaller image than you're giving it. Look again at the form's instructions: a "photo under 50 KB" usually expects a passport-style head-and-shoulders picture of a few hundred pixels, not a full-resolution shot.