Why convert between image formats
Different formats suit different jobs. JPEG is the standard for photographs: small files, no transparency. PNG is lossless and supports transparency, which suits logos, screenshots and graphics with text. WebP, developed by Google, can produce smaller files than either, and is supported by all modern browsers, but some older software and upload forms still insist on JPG or PNG. A converter lets you switch quickly when a form rejects your file, when you need transparency or when you want a lighter file for a website.
How the conversion works
Your browser decodes the picture into raw pixels, draws it on a canvas, and encodes it again in the format you choose. Any file type your browser can display will load, which usually includes PNG, JPG, GIF (first frame), WebP, BMP and SVG, and sometimes AVIF. HEIC photos from iPhones are only readable in some browsers, such as Safari. Animated GIFs and WebP files become a single still frame.
Transparency and backgrounds
PNG and WebP can hold transparent pixels; JPEG cannot. When you convert a transparent image to JPG, the empty areas are filled with the background colour you pick, white by default. Choose a different colour if the picture will sit on a dark page. Converting a JPG to PNG does not restore anything: it just stores the same pixels losslessly, so the file often becomes larger.
Quality and file size
- Quality applies to JPG and WebP. Around 90% to 92% keeps most images visually identical.
- PNG ignores the slider because it is always lossless.
- Photos as PNG are often several times larger than the same photo as JPG.
- If your browser cannot write WebP, it silently produces PNG instead, and the table tells you which format was actually created.
Privacy
Everything is done on your device. The images are not uploaded, and the downloads are temporary files created in your browser's memory. The converted files do not carry over camera metadata such as location tags.