How to Compress an Image to 100KB, 50KB or 20KB (Without It Looking Awful)

You have a perfectly good photo, and the upload form says "maximum size 100 KB". Your photo is 3 MB. Here is how to get from one to the other without turning your face into a smudge.

Why some images are so big in the first place

File size comes from three things: how many pixels the picture has, how hard it is compressed, and the format it is saved in. A modern phone photo is often 4,000 pixels wide or more. That is fantastic for printing a poster and complete overkill for a passport-photo box on a website.

The good news is that this means you have three levers. Cut the pixels, raise the compression, or change the format. Almost every "how do I reduce image size in KB" problem is solved by pulling one or two of them, in that order.

The fast way: compress to a target size

If you just want the result, use a compressor that lets you type the size you need. That way you are not guessing at quality sliders and re-uploading five times. With our image compressor, it goes like this:

1. Add your photo (or several, up to 50 at a time).
2. Leave "Compress by" on Target size and pick 100 KB, or 50 KB, or 20 KB. You can also enter a custom number.
3. Press Compress. The tool tries different quality levels to find the best-looking version that fits under your limit. If quality alone cannot get there, it also shrinks the dimensions a bit.
4. Download it, and check the preview before you upload.

Nothing is uploaded while this happens. The work is done by your own browser, which is a nice bonus when the photo is a passport picture or an ID card.

When 100KB still looks bad: do this first

Squeezing a 12-megapixel photo into 20 KB by compression alone will always look rough, because there are simply too many pixels to describe in so few bytes. The trick is to reduce the size before compressing.

• Resize first. Use Resize Image to bring the width down to what the form actually needs. For a small profile picture, 600 pixels wide is often plenty.
• Crop out the extras. Empty background eats bytes for no benefit. A tight crop with Crop Image gives the face more of the pixel budget.
• Use JPG for photos. PNG is wonderful for screenshots and logos and terrible for photographs. If your file is a PNG photo, converting it to JPG is often the single biggest saving.
• Try WebP if the site allows it. It usually beats JPG at the same look, but many government and school portals only accept JPG, so check the rules.

Rough guide: what size to aim for

There is no universal rule, because it depends on the picture. Detailed scenes need more bytes than a plain background. But as a very rough starting point for a normal photo:

Treat those widths as a place to start experimenting, not a promise. Always look at the result before you submit it.

Passport photos, signatures and ID scans

These are the cases where people get stuck, because the requirements are strict and the stakes feel high. A few things that help:

• Read the exact requirement on the portal. Some want a specific pixel size and a file-size range. Set the dimensions first with the resizer, then hit the size range with the compressor.
• For a signature, sign in dark ink on plain white paper, photograph it in even light, crop tightly, and then compress. Fewer details in the picture means it will survive a small file size much better.
• Do not stretch. If you type both width and height, keep "Keep aspect ratio" on unless the portal demands an exact shape, in which case crop to that ratio instead of squashing.
• Keep the original. Save your compressed copy under a new name so you can always go back.

Mistakes that make things worse

• Taking a screenshot of the photo. It looks like a shortcut but you lose quality and often gain a PNG that is bigger than what you started with.
• Converting a JPG to PNG "to keep quality". Converting cannot restore detail that is already gone, and the file gets much bigger. See JPG vs PNG vs WebP for why.
• Compressing the same file again and again. Every round of lossy compression adds artefacts. Always go back to the original and compress once.
• Renaming .png to .jpg. That does not convert anything. The file is still a PNG with a wrong name, and some sites will reject it.

Is it safe to compress private photos online?

It depends on how the tool works. Many sites upload your file to their servers. Ours does not: the compression runs locally in your browser, so the image stays on your device. We wrote more about how to tell the difference in Are online file converters safe?.

Quick answers

How do I reduce image size in KB without losing quality?

You cannot shrink a file a lot without some loss, but you can make the loss hard to see. Resize to the dimensions you really need first, then compress at a quality of roughly 70 to 85 percent. Most people cannot spot the difference at normal viewing size.

Can I compress to exactly 100 KB?

You can get very close. The tool aims for the largest quality that still fits under your target, so the result is usually just below the limit rather than exactly on it.

What is the best format for small files?

JPG for photos when compatibility matters, WebP if the destination accepts it, and PNG only for screenshots, logos and graphics with flat colours.