How to compress a JPG to 20KB
- Select Choose files, or drop a JPG photo on the box.
- The tool aims for under 20KB, which is 20,480 bytes here. It tests quality levels from 95 down to 40 percent and keeps the sharpest result that fits.
- If 40 percent is still too big, it shrinks the width and height by 15 percent at a time until the file fits.
- Select Download. The result ends in
-compressed, so your original is untouched.
Where a 20KB limit comes from
JPG is the format most small-size limits are written for. A JPG-only field with a 20KB cap is typical of photo and signature uploads on application forms.
What 20KB means in pixels
20KB is 20,480 bytes, or 163,840 bits. Divide that by the number of pixels and you get the bits each pixel can use. Photos look fine at about 1.5 bits per pixel or more, and the table shows how common sizes fare at 20KB.
| Picture size | Pixels | Bits per pixel | At 20KB |
|---|---|---|---|
| 640×480 | 307,200 | 0.53 | soft, expect some shrinking |
| 1024×768 | 786,432 | 0.21 | too tight, the tool shrinks the picture |
| 1600×1200 | 1,920,000 | 0.09 | too tight, the tool shrinks the picture |
| 4000×3000 | 12,000,000 | 0.01 | too tight, the tool shrinks the picture |
At 1.5 bits per pixel, 20KB holds a picture of about 382×287 pixels in a 4:3 shape (109,634 pixels). Expect the output to stay a JPG every time. To reach 20KB the tool lowers quality towards 40 percent and, when that is not enough, trims the width and height in 15 percent steps. It reports the final pixel size so you can compare it with the form.
About the output format
This page accepts JPG files only and always saves a JPG, so it is the right choice when a form says “JPG only”. The output format is fixed, unlike the general 20KB page, which accepts PNG and WebP too.
Tips
- If your file is a PNG, convert it with PNG to JPG first.
- Save the file with the .jpg extension. Some forms check the extension as well as the content.
- Plain backgrounds shrink best. A cluttered picture ends up smaller in pixels to fit.
- See also: compress image to 20KB, compress JPG to 50KB, PNG to JPG, image compressor.
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