How much smaller will the JPG be?
It depends entirely on content. PNG stores every pixel losslessly, so it is the wrong format for photographs in the first place — which is where the biggest savings come from:
| Content | Typical saving | Notes |
|---|---|---|
| Photograph saved as PNG | 80–90% | The classic wrong-format case |
| Screenshot with imagery | 60–80% | Good candidate |
| Screenshot, mostly text | 40–70% | Watch for halos around text |
| Logo / icon with flat colour | often larger | Keep PNG, or use WebP |
| Anything transparent | n/a | Transparency is lost — use WebP |
Frequently Asked Questions
Why convert PNG to JPG?
File size. PNG is lossless, so photographs and screenshots saved as PNG are often several times larger than they need to be. Converting to JPG at quality 90 typically cuts the file by 70–90% with no visible difference on photographic content. It also helps when a site, form, or piece of software only accepts JPG.
Are my files uploaded anywhere?
No. The PNG decoding and JPEG encoding run entirely in a Web Worker on your device using WebAssembly builds of the standard libpng and JPEG libraries. Your files never leave your browser — you can confirm by watching the Network tab during conversion.
What happens to transparency?
JPG does not support transparency. Any transparent areas in the PNG are flattened onto a solid background during conversion. If your image has transparency you need to keep — a logo or icon, for example — convert to WebP instead, which supports both good compression and an alpha channel.
What quality setting should I use?
Quality 90 (the default here) is visually indistinguishable from the original for almost all content. Drop to 80 if you want smaller files and can accept very minor softening. Below about 70, JPEG artifacts become visible around sharp edges and text — which is why screenshots with a lot of text sometimes look better kept as PNG or converted to WebP.
Will converting a screenshot to JPG look worse?
Possibly. JPEG compresses smooth photographic gradients extremely well but struggles with the hard edges of UI text, where it can produce faint halos. For screenshots that are mostly text, WebP usually gives you both the small file size and clean edges. For screenshots that are mostly imagery, JPG at quality 90 is fine.
Checking images at scale?
Bulk-audit hundreds of URLs at once or hit a dimensions API from your own code.
Related tools
- JPG to PNG converter — the reverse.
- PNG to WebP converter — smaller than JPG and keeps transparency.
- Image formats compared: WebP vs PNG vs JPEG.