Compress an Image to 50 KB

For a head-and-shoulders photo at the sizes forms normally display, yes. Fifty kilobytes is 409,600 bits. Spread over a 600 x 800 image (480,000 pixels) that is about 0.85 bits per pixel, which JPG and WebP can use to produce a recognisable, reasonably clean photo. Spread over a 3000 x 4000 phone photo it is about 0.03 bits per pixel, which is not enough for anything.

So the size you upload matters as much as the quality setting. If the form gives pixel dimensions, use them. If it does not, a few hundred pixels on the long side is usually plenty for an ID or profile photo.

The tool first draws your image at full size (anything longer than 4096 pixels on its long side is reduced to 4096 px) and encodes it at quality 0.8. If that file is already at or under the target (and not larger than your original), you get it straight away. If not, it repeats up to 10 times. On each pass it multiplies the quality by 0.95 (0.85 for PNG) and, because the first attempt was too big, also shrinks the width and height to 95% of the previous pass.

Ten passes is the limit. After all ten, the width and height have dropped to about 60% of where they started and the quality setting to about 0.48. If the file is still too big at that point, you get the last attempt and a note saying the target was not reached.

• Resize first with the Image Resizer to the dimensions you need. The tool then only has to lower the quality, not the size.
• Crop out background you do not need with the Crop tool.
• Choose JPG if the form requires JPG. Otherwise WebP generally looks better at the same size.
• Compare with the preview slider. Look at edges such as hair and glasses, where compression artifacts show first.

If the photo looks too soft at 50 KB and the form allows more, try 100 KB. For signatures and thumbnails, 20 KB is usually enough. For any other limit, type it into Reduce Image Size.

The photo is processed in your browser and is not uploaded.