Convert PNG to JPG

PNG to JPGの使い方

1. 1

   Drop the PNG files

   Add up to 10 PNG screenshots, exports or downloads of up to 25 MB each; other formats can join the same batch.

2. 2

   Choose a fill colour

   Transparent parts of a PNG become white in the JPG. Pick another colour under Quality if the image will sit on a dark page.

3. 3

   Set the quality

   90 is preselected: near-invisible loss at a fraction of the PNG's size. Lower it for email attachments, raise it for print.

4. 4

   Download

   Each file keeps its name with .jpg at the end; save them one by one or as converted-jpg.zip.

PNG to JPG について

PNG stores every pixel exactly, which is perfect for screenshots, diagrams and logos but heavy for photographs: a 12-megapixel photo saved as PNG can easily weigh 20–30 MB. JPG throws away detail the eye barely notices and usually brings the same picture down to 2–5 MB at quality 90, which is why upload forms, email clients and print shops so often ask for JPG instead.

This page decodes each PNG and encodes it with MozJPEG at the quality you choose. Two things change on the way. First, transparency: JPG has no alpha channel, so transparent and semi-transparent areas are flattened onto a fill colour, white unless you pick another. A logo with soft edges therefore keeps a smooth outline against that colour, but it will show a box if you later place the JPG on a different background. Second, sharp edges: JPG compression works in 8 × 8 blocks and can leave faint ripples around text, thin lines and flat areas of colour, which is most visible on screenshots with small type.

So the conversion is a good idea for photos, photo-heavy screenshots and scans, and a poor one for icons, interface mock-ups and graphics with large flat colours, which often stay smaller and crisper as PNG. The pixel dimensions don't change, and any text chunks or metadata inside the PNG are not copied. If you need a small file and transparency together, choose WebP instead under Convert to.

主な機能

PNG to JPG：よくある質問