Why an exact file size can be difficult
An image encoder cannot always make a particular picture fit a precise byte limit while keeping its current dimensions and acceptable quality. Photos with detail or texture can take more data than simple graphics. The output format, quality setting, and pixel dimensions also affect the result.
Treat the requested size as a ceiling or goal. Always check the measured output and the destination's rules before uploading it. This tool measures kilobytes in decimal units: 1 KB is 1,000 bytes.
A reliable workflow
- Check the upload site's file-size limit and any required image dimensions or format.
- Set the target size, then choose a format accepted by the destination. JPEG or WebP can use lossy quality settings; PNG does not have a lossy quality control here.
- If the image is still over the target, allow smaller dimensions when the upload rules permit it. Fewer pixels can reduce the file size while keeping the aspect ratio.
- Review the actual size, dimensions, and preview. Keep the original in case you need to try a different setting.
When the target is not reached
The best result may stay above the target when reaching it would require going below the tool's quality floor or allowed dimensions. For PNG, the browser encoder does not offer a lossy quality slider, so reducing dimensions may be the only additional size-reduction option in this workflow.
Try a format the destination accepts, reduce dimensions if allowed, or check whether the destination accepts a larger file. Do not keep lowering quality if the image becomes difficult to read or use.