PNG to JPG converter
Your images never leave this device
This is the conversion that actually saves space. A PNG screenshot or photograph stores every pixel exactly and gets enormous; the same image as a JPG is routinely a tenth of the size with no visible difference. The catch is that JPG throws detail away permanently and cannot hold a transparent background.
How to convert PNG to JPG
Whether this is a good idea depends entirely on what is in the image. Photographs and screenshots of photographs convert brilliantly, because JPG was designed for exactly that kind of continuous tone. Logos, diagrams, screenshots of text and anything with hard edges convert badly: JPG smears a faint halo around every sharp boundary, and on a screenshot of a spreadsheet that is immediately obvious. Keep those as PNG, and use this for the pictures.
Questions
JPG compresses in eight-by-eight blocks and struggles with hard edges. For logos, line art and text, PNG is the right format and converting it is a step backwards.
It is replaced with white. JPG has no alpha channel, so a transparent PNG needs something laid behind it.
For a photograph, typically five to fifteen times. For a flat-colour graphic, sometimes nothing at all, or larger.
You can convert the file back, but the detail JPG discarded is gone for good. Keep the original PNG if you might need it.
No. The conversion happens in this page using the browser’s own image pipeline.