Reduce Image Size in KB to an Exact Range and Size
Set the KB range your form asks for (such as 10–20 KB or 20–50 KB) and, if it asks, the dimensions in pixels or cm. One step, one file that fits both.
or drop it here, or paste with Ctrl+V. JPG, PNG, WebP or HEIC (iPhone).
How to reduce image size in KB
- Choose, drop or paste your image. JPG, PNG, WebP and iPhone HEIC photos all work.
- Enter the file size your form asks for. Click a range such as 20–50 KB, or a maximum such as 50 KB, or type your own numbers. The minimum is optional.
- If the form also gives dimensions, set them in pixels or centimetres. Otherwise leave dimensions on “Original”.
- Check the preview and the numbers under it, then download the file.
The tool re-saves your image at different quality levels and keeps the highest quality that still fits under your maximum. It usually takes a few seconds, even for a 12-megapixel phone photo, and you can cancel at any time.
File size and dimensions are two different limits
Application forms often ask for both: a file size such as “20 KB to 50 KB” and dimensions such as “200 × 230 pixels” or “3.5 cm × 4.5 cm”. File size is how many bytes the file takes up. Dimensions are how many pixels wide and tall the picture is. A photo can have the right dimensions and still be too heavy, or the right weight and the wrong shape.
Many compressors only take a maximum, and some quietly cut the width and height in half to hit a small target without mentioning it. Then you resize in one place, compress in another, and still get “file too small” or “wrong dimensions”. Here you set both limits at once. If you set dimensions, the result has exactly those dimensions and only the quality changes. If you leave dimensions open, quality stays at 70 or above and the picture is made smaller only when that is the only way to fit; the new size is shown in a highlighted note so you can check it against your form.
When the form has a minimum size
Many application forms reject files that are too small as well as too big: a signature of 10–20 KB, a photo of 20–50 KB. A signature saved at 140 × 60 pixels is mostly white paper, so even at the best quality it is often only 3 to 8 KB. Making it bigger in pixels would break the dimension rule, and the quality is already at the top. In that case the tool adds blank comment data inside the file until its size is a little above your minimum. The file is still a normal JPG: image viewers skip the comment and show the same picture, and the result shows how many bytes were added.
The minimum is counted the strict way too: a 10 KB minimum means at least 10,240 bytes, which is 10 KB whether the website counts 1 KB as 1,000 or 1,024 bytes.
What counts as 1 KB?
Windows counts 1 KB as 1,024 bytes, while macOS and many websites count it as 1,000 bytes. Instructions on forms rarely say which one they mean. To be safe, Reduce Image Size in KB treats 1 KB as 1,000 bytes: a 50 KB limit means at most 50,000 bytes, which is also under 50 KB when counted the other way. The result shows the exact number of bytes and both readings, so you can compare it with what your computer or the website shows.
Converting centimetres to pixels
Images are stored in pixels, so a size in centimetres has to be converted using a resolution in dots per inch (DPI). The formula is pixels = centimetres ÷ 2.54 × DPI. Scanning guidelines for many online applications ask for 200 DPI, so that is the default here: 3.5 × 4.5 cm becomes 276 × 354 pixels. If your notice mentions 300 DPI, type 300 and the pixel size updates (413 × 531 pixels for the same photo).
Tips for a sharper result at a small size
- Crop away empty space first. Fewer pixels of background leave more of the limit for your face or signature.
- A plain, evenly lit background compresses much better than a busy one.
- For a signature, sign with a dark pen on white paper and crop close to the ink. Signatures are mostly white, so they reach small sizes without losing detail.
- Keep JPG unless the form asks otherwise. PNG cannot lower its quality, so the only way to make a PNG smaller is to reduce its dimensions.
Private by design
Your image is processed by your own browser and is never sent to a server, so a large photo does not have to travel over a slow connection. The file you download contains only the picture, without the location and camera details stored in the original photo.
Frequently Asked Questions
How do I reduce image size in KB?
Choose your image, then enter the size your form asks for: click a range such as 20–50 KB, or a maximum such as 50 KB, or type your own numbers. The tool tries different JPG quality levels, keeps the best-looking version that fits, and gives you a download button.
Will the file really be under the limit on the application website?
Yes. Some websites count 1 KB as 1,000 bytes and others as 1,024 bytes, and most forms do not say which. This tool always uses 1,000 bytes, the stricter of the two, so a file made for 50 KB is at most 50,000 bytes and passes either way. The exact byte count is shown next to the result.
Does it change the width and height of my photo?
Only if you allow it, and it always tells you. If you set dimensions in pixels or centimetres, the result has exactly those dimensions. If you leave dimensions on “Original”, the tool keeps quality at 70 or above and makes the picture smaller when that is the only way to fit, showing the new pixel size in a highlighted note. Choose “Keep original exactly” to never resize.
How do I make a photo 3.5 cm × 4.5 cm?
Under Dimensions choose “Set in cm”, enter 3.5 and 4.5, and keep 200 DPI unless your form names a different DPI. At 200 DPI that is 276 × 354 pixels. If your photo has a different shape, pick whether to crop it, add white edges or stretch it.
Can I use a HEIC photo from an iPhone?
Yes. Choose the HEIC file as it is. Safari opens it directly; in other browsers the tool loads a HEIC decoder the first time (about 3 MB) and converts the photo on your device.
Is my photo uploaded?
No. Everything happens in your browser, and the image never leaves your device. The new file also does not carry the camera data from the original, such as GPS location.
My form also has a minimum, like 10–20 KB. What if the file is too small?
Type the minimum in the Minimum box, or click a range such as 10–20 KB. Small, plain images like a 140 × 60 pixel signature often stay under 10 KB even at the best quality. Then the tool adds blank comment data inside the file until it is a little above your minimum. The picture and its pixel size do not change, and the result tells you how many bytes were added.