How to Compress an Image to 20 KB, 50 KB or 100 KB

To get a photo under 20 KB, 50 KB or 100 KB, you shrink two things: its pixel dimensions and its JPEG quality. The quickest way is the resize image in KB tool: add the photo, choose "Under 20 KB", "Under 50 KB" or "Under 100 KB", press Resize image and download the JPG. It works out the pixel size and quality for you, and it runs in your browser, so the photo is never uploaded.

If you would rather choose the settings yourself, resize the photo first and then compress it with the image compressor. This guide explains how pixel size, quality and file size relate, gives approximate pixel sizes that fit each limit (measured on real photos), and shows when to use which tool. For SSC, IBPS and UPSC photo and signature rules, see the separate guide to resizing a photo and signature in KB for exam forms.

The quick way: let the KB tool hit the target

1. Open the KB resizer and add your photo. It accepts JPG, PNG and WebP. An iPhone HEIC photo needs converting first with the HEIC to JPG converter.
2. Choose a preset: Under 20 KB, Under 50 KB, Under 100 KB or Under 200 KB. For any other limit, choose Custom and type the number in the Maximum size box.
3. Leave width and height blank unless the form asks for exact pixels. Blank boxes let the tool pick the best pixel size itself.
4. Press Resize image and read the result line, for example "631 × 419 px · 48.0 KB · quality 70%".
5. Download the JPG and upload that file.

Behind the button, the tool tries different JPEG quality levels and keeps the highest one that fits under your limit. If the quality would have to fall below about 60%, it makes the picture smaller instead, because a smaller, clean photo looks better than a full-size blotchy one. It counts the maximum in 1,000-byte KB, so the file passes whichever way the portal counts.

This is what it did with two real test photos in Chrome:

The plain-background portrait kept more than twice as many pixels as the street scene for the same 50 KB. That is the first lesson about file size: what is in the picture matters as much as how big it is.

How pixel size, JPEG quality and file size relate

The size of a JPG depends on three things.

• Pixel count (width × height). Halving both the width and the height leaves a quarter of the pixels. In our test, the street photo at 1600 × 1200 px and quality 75 was 291 KB; at 800 × 600 px it was 92.5 KB, about a third.
• Quality setting. JPEG splits the picture into small blocks and throws away the fine detail your eye is least likely to miss. A lower quality number throws away more.
• Content. Plain walls, clear sky and smooth skin compress well. Leaves, crowds, printed text and the grainy noise of photos taken in dim light do not.

Lowering quality saves a lot at first and then less and less. Here is the same 800 × 600 px street photo saved at different qualities:

Going from 90% to 75% cut the file by 40%. Going from 50% to 40% saved only another 14% and started to show blocks. So the rule is: cut pixels first, then quality. If you have to go below about 50% quality to reach a limit, the picture still has too many pixels.

The format matters too. JPG is lossy and made for photos; PNG is lossless and stores every pixel exactly, which makes photos huge. The same 1600 × 1200 px street photo was about 4.1 MB as a PNG against 291 KB as a JPG at quality 75. If your photo is a PNG (screenshots and some edited photos are), convert it with the PNG to JPG converter, or just use the KB resizer or compressor, which both save JPG. The guide to JPG vs PNG vs WebP explains the formats in detail.

Pixel sizes that fit under 20, 50 and 100 KB (approximate)

These sizes come from four real photos cropped to the usual 4:3 phone shape and saved as JPG in Chrome at quality 75, the image compressor's default. Treat them as a starting point, not a promise: your photo can come out 30–50% bigger or smaller depending on detail, noise and browser.

At quality 50 you can go roughly 20% larger in each direction for the same limit. In our tests the busy street photo fitted under 100 KB at 1000 × 750 px and quality 50 (86 KB), against 800 × 600 px at quality 75. For forms, which show your photo small anyway, the smaller picture at 75 usually looks cleaner.

Image compressor or KB resizer: which one to use

A few details are worth knowing before you choose:

• The image compressor keeps the pixel size and changes only the quality (a slider from 10% to 100%, starting at 75%). It always saves a JPG, so transparent areas of a PNG turn white. It warns you if the result is bigger than your original, which happens when the original was already heavily compressed. It also accepts HEIC photos directly.
• The image resizer sets an exact width and height but has no aspect-ratio lock, so work out the height yourself: new height = new width × original height ÷ original width. A 4000 × 3000 photo resized to 1200 px wide needs 1200 × 3000 ÷ 4000 = 900 px tall. It saves a JPG at quality 92, so compress afterwards if you need a small file.
• The KB resizer keeps the shape if you fill in only the width or only the height. Fill in both and it either crops the picture to fill that exact box or fits it inside with a white border.

Step by step with the image compressor

1. If the photo is far larger than you need, resize it first with the image resizer to roughly the size in the table above.
2. Open the image compressor and add the photo (JPG, PNG, WebP, GIF or HEIC).
3. Leave quality at 75% and press Process image. The result line shows the new pixel size and KB, for example "800×600 · 92 KB".
4. Still too big? Lower the quality in steps of 5 to 10 points and press Process image again. Every attempt starts from your original, so retrying does not stack up damage.
5. If you reach about 50% and are still over the limit, go back to step 1 and make the picture smaller.
6. Compare the before and after previews, then press Download result. The file name ends in -ethicalfusion.jpg.

Sensible targets for email and websites

Email and chat. A photo 1600 px on its long side at quality 75 to 80 looks sharp on any phone or laptop screen. In our tests that came to roughly 140–320 KB per photo, so ten photos fit easily in one email instead of the 30–50 MB the camera originals would take.

Websites. Size each image to the largest width it is actually shown at (a 4000 px photo in an 800 px column only slows the page), use quality 70 to 80, and consider WebP: at the same quality setting it came out 23–50% smaller than JPG in our tests. The WebP converter does this in Chrome, Edge or Firefox. The guide to compressing, resizing and converting images for the web covers the rest.

Forms. Use the KB resizer with the form's exact limit, and check whether the form also sets a minimum size or exact pixel dimensions. Many do.

Mistakes that make photos blurry or keep them too big

• Starting from a forwarded copy. Photos sent through chat apps are usually compressed already, and compressing them again adds a second round of damage. Start from the original camera file.
• Taking a screenshot to shrink a photo. It changes the pixel size unpredictably and usually saves a PNG, which is often bigger than the photo you started with.
• Compressing the same file again and again. Every JPG save loses a little more. Keep the original untouched and make each smaller version from it.
• Renaming .png to .jpg. That changes only the name, not the format, and some portals reject the file. Convert it properly.
• Enlarging a small image. Stretching a 200 px photo to 600 px adds pixels and KB but no detail.

Frequently asked questions

How can I compress a photo to 20 KB without losing quality?

Some loss is unavoidable at 20 KB, but it need not be visible. Bring the photo down to about 300–400 px on its long side and keep the quality around 60–75%. Forms display photos small, so at that size the difference from the original is hard to see. The KB resizer's "Under 20 KB" preset finds this balance for you.

Why is my image still over 100 KB after compressing?

Usually the pixel size is still too large. A 4000 × 3000 phone photo cannot reach 100 KB at a sensible quality; resize it to about 800–1000 px wide first. Also check that the file is really a JPG and not a PNG with a renamed extension.

Can I compress a PNG and keep its transparent background?

Not with the image compressor or KB resizer, which save JPGs with a white background. To keep transparency in a smaller file, use the PNG to WebP converter in Chrome, Edge or Firefox. Safari cannot create WebP files from a web page, so there the tool saves a PNG instead.

Do I need to change the DPI?

Usually not. DPI is only a printing note stored inside the file; it does not change the pixels or the KB. If a form gives limits in KB and pixels, match those two numbers.

Why does a file made for a 20 KB limit show as 19.5 KB?

The KB resizer keeps the file under 20,000 bytes, so it passes portals that count 1 KB as 1,000 bytes, but it displays sizes in 1,024-byte KB. It is under the limit either way.

Is my photo uploaded anywhere?

No. The image tools draw and re-save the picture inside your browser tab. The file goes nowhere until you upload it to the form yourself.