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How to Compress an Image to Under 100 KB (Without Making It Look Bad)

You pick a photo, press upload, and the form answers with a red message: file too large, maximum 100 KB. The picture on your phone is a few megabytes. Job portals, admission forms, ID uploads and plenty of government sites do this, and they almost never tell you how to fix it.

It turns out to be a two-minute job once you know what actually makes an image file big. Here is how to get under 100 KB without turning your photo into mush.

What makes an image file big

Three things control the size: how many pixels the picture has, how hard it is compressed, and which file format it is saved in. Of the three, the pixel count matters most.

A modern phone camera produces pictures that are thousands of pixels wide. The photo box on a form might show your face at a few hundred pixels. All that extra detail is stored in the file and nobody ever sees it. Cut the width and height in half and the picture has only a quarter of the pixels, which usually shrinks the file by far more than you would expect.

The quick way: use the image compressor

1. Open the Image compressor and choose your photo.
2. Type a maximum width. Around 800 pixels is a sensible start for a portrait. Leave the box empty to keep the original dimensions.
3. Leave the quality at 70 for the first try.
4. Press Compress. The tool shows the size before and after, and how much you saved.
5. Still above 100 KB? Lower the width a little and compress again. Comfortably below? Download it.

The tool always starts from the original file you picked, so you can try as many settings as you like without damaging anything. The photo is processed inside your browser and is never uploaded, which matters when the picture is an ID card or a passport photo.

Resize first, then lower the quality

Quality is a slider you can drag down until the file is small enough, and it is tempting to do just that. The trouble is that low quality shows. Edges turn blocky, flat areas pick up blotches and text goes fuzzy. Shrinking the dimensions loses detail too, but it is detail you could not have seen at the size the picture is displayed anyway.

So the order that works best is: reduce the width first, keep the quality somewhere around 70 to 80, and only nudge it down if you still need to. If you catch yourself going below 50 or so, shrink the width instead.

JPG, PNG and why the format matters

JPG is built for photographs. It throws away detail the eye barely notices, which is why photos saved as JPG are small. PNG keeps every pixel exactly. That is great for logos, screenshots and anything with sharp text on flat colour, but a photograph saved as PNG is usually several times bigger than the same photo as a JPG.

The compressor saves your result as a JPG. That suits photos, signatures and document scans. The one catch is transparency: if your image has a see-through background, it will come out with a white one.

Settings that usually work

• Passport-style photo: about 600 to 800 pixels wide, quality 70.
• Signature: crop close to the signature first, then try 400 to 600 pixels wide. A signature is mostly white paper and compresses very well.
• ID card or certificate scan: the text has to stay readable, so keep the width around 1000 to 1200 pixels and lower the quality only a little. If the text looks soft, raise the quality before you raise the width.

These are starting points, not rules. Every picture compresses differently, so look at the size shown after each try.

Mistakes that waste time

• Compressing a compressed copy. Each time a JPG is saved again it loses a little more detail. Go back to the original every time.
• Taking a screenshot of the photo. It changes the proportions and the quality in ways you do not control.
• Renaming a PNG to .jpg. The name changes, the file does not. It will still be large.
• Deleting the original. Keep it. You will want the full-size version sooner or later.

The short version: shrink the width, start at quality 70, check the number and adjust once or twice. That is enough for most forms.