When JPG beats PNG
PNG and JPG solve different problems. PNG is lossless: every pixel survives exactly, which is perfect for screenshots, logos and diagrams but wildly expensive for photographs. JPG was built for photos. It discards fine detail your eye barely registers and shrinks the file dramatically in return. If you have a photo saved as a PNG, perhaps exported from an editor or captured as a screenshot, converting it to JPG usually cuts the file size by three quarters or more with no visible difference.
Smaller files matter more often than people expect: email attachment limits, website upload caps, form fields that reject anything over a few megabytes, and simple storage. Converting is often the difference between an upload failing and sailing through.
What the converter does
Your browser decodes the PNG, draws it onto an invisible canvas and re-encodes it as a JPG at the quality you choose. Because JPG has no transparency, any transparent areas are filled with white first; without that step they would render as black in many viewers. Everything runs on your device. The image is never uploaded, never stored and never seen by anyone else.
Underneath, both formats are compressing the same raw grid of pixels:
PNG compresses that grid without losing anything; JPG compresses it much harder by letting some detail go. The before and after rows show you what that difference is worth for your particular image.
Reading the before and after sizes
The tool shows the original PNG size, the new JPG size and the change between them, updating live as you move the quality slider. A big saving is normal for photos and nothing to worry about; a small saving, or a JPG that comes out larger, is a hint that the image was a poor fit for JPG in the first place.
When to keep the PNG
Keep the PNG when the image contains text, sharp lines or large areas of flat colour: screenshots, logos, charts, icons and interface mock-ups. JPG artefacts show up worst exactly there. Keep it too when transparency matters, since the conversion fills transparent areas with white, and when you expect to edit the image again, because each JPG save loses a little more quality. For everything photographic that just needs to be sent, uploaded or stored, JPG is the sensible choice, and the slider lets you decide exactly how much size you trade for quality.
Frequently asked questions
Why is the JPG so much smaller than my PNG?
PNG is lossless, so it keeps every pixel exactly and pays for it in file size, especially for photos. JPG is lossy: it throws away detail your eye barely notices, which is why a photo can shrink by 80% or more with no obvious change. The before and after rows show you exactly what you saved.
What happens to transparent areas?
JPG has no transparency, so any transparent parts of the PNG are filled with white before converting. If your image needs a transparent background, for example a logo going onto a coloured page, keep it as a PNG.
What quality setting should I choose?
The default of 92% is visually identical to the original for almost everything. Between 80% and 95% is the useful range for most photos. Below about 75% you will start to see blockiness and smudging, particularly around text and sharp edges.
When should I keep the PNG instead?
Keep PNG for screenshots, logos, diagrams, text and anything with sharp edges or flat colour, because JPG compression visibly smears those. Also keep PNG if you plan to edit the image again, since every JPG save loses a little more quality.
Is my image uploaded anywhere?
No. The conversion happens entirely in your browser using the canvas element. The image never leaves your device and nothing is stored.