How to use the reduce image size in KB
- 1Type the limit into Target size and choose KB or MB, or press a quick button such as 50 KB.
- 2Press Choose images, drag images in, or paste one with Ctrl+V. Each image is compressed straight away.
- 3Read the result row: size in KB and exact bytes, dimensions and quality. Press Preview to compare before and after.
- 4Press Download on a row or Download all (ZIP). Change the target at any time and the images update.
How the limit is counted
Target size: 50 KB
Limit used: 50,000 bytes (1 KB = 1,000 bytes) With 1 KB = 1,024 bytes: 51,200 bytes
A file saved under 50,000 bytes passes both kinds of check, which is why 1,000 is the default.
Setting a target size
Enter the number the form or website states, not a rounder one: if the limit is 50 KB, type 50. The quick buttons cover the most common limits from 20 KB to 1 MB.
By default 1 KB counts as 1,000 bytes, so a 50 KB target means at most 50,000 bytes. Some upload forms count 1 KB as 1,024 bytes (51,200 bytes for 50 KB); a file made with the 1,000-byte setting passes both. Switch 1 KB equals to 1,024 bytes under More options only if you know the form uses binary kilobytes and want the extra quality. Every result shows its exact byte count so you can compare it with the limit yourself.
How the tool reaches the target
- It saves the image as a high-quality JPG. If that already fits, you get that file.
- If not, it searches for the highest quality that fits. The search halves the range each time, so it needs about seven tries rather than dozens.
- If even medium-low quality is too big, it reduces width and height in proportion and searches again. It prefers a slightly smaller picture at decent quality over a larger, blocky one.
An image that is already under the target, in the same format, is left untouched and you download the original. Press Re-save on that row if you still want it re-encoded, for example to remove location data. Re-saved images have their location and camera details (EXIF) removed.
When the target is too small
Small targets force small dimensions. As a rough guide, at medium JPG quality (about 1–2 bits per pixel) the longer side of a 4:3 photo comes out around:
| Target | Approximate longer side |
|---|---|
| 10 KB | 230–330 px |
| 20 KB | 330–460 px |
| 50 KB | 520–730 px |
| 100 KB | 730–1,030 px |
| 200 KB | 1,030–1,460 px |
Plain backgrounds keep more pixels; busy scenes fewer. If you switch off Allow smaller dimensions if needed, only quality is lowered, and when even the lowest quality is too big the row shows the smallest file it could make with a warning. To get more out of a small target, crop away background first with the crop tool, or tick Black and white (grayscale) for scanned documents and signatures.
Common targets for application forms
| Upload | Limits often seen | Tip |
|---|---|---|
| Signature scan | 10–20 KB | Crop tight to the ink and use grayscale |
| Passport-style photo | 20–50 KB, sometimes up to 100 KB | Keep the face large in the frame |
| ID or certificate scan | 100–300 KB | Grayscale saves a lot on paper documents |
| CV or portfolio image | 200 KB–1 MB | Quality matters more than pixels |
These are typical ranges, not any organization's rules. Use the numbers printed on the form you are filling in; requirements differ and change over time. Fixed-size pages exist for the most common limits, such as compress image to 20KB and compress image to 50KB.
KB limits vs pixel requirements
A KB limit is about file size; a pixel requirement such as 200 × 230 px is about dimensions. They are separate checks, and a form can enforce both. This page meets the KB limit and keeps your photo's proportions. You can cap the size with Max width and Max height, but the image only fits inside them.
If the form gives exact dimensions, or a size in cm or mm, use the photo resizer in KB. It crops to the required shape, sets the exact pixels and then meets the KB range.
Are my files uploaded?
This tool runs entirely in your browser. Your files are not uploaded to our servers.