The short answer
Use JPEG for broadly compatible photographs when transparency is not needed. Use PNG for crisp graphics or transparency when a lossless file is useful. Consider WebP for web delivery when the browsers and tools in your workflow support it.
No format is smallest for every image. A flat icon, a detailed photograph, and a transparent illustration compress differently, so compare the actual exported files.
JPEG: familiar and widely supported
JPEG uses lossy compression and is supported by virtually all image viewers and browsers. It is often a practical format for photographs, but repeated lossy edits can accumulate visible artifacts. JPEG has no alpha transparency, so transparent areas must be flattened onto a background.
PNG: transparency and lossless pixel data
PNG is useful for screenshots, diagrams, logos, and images that need alpha transparency. It preserves the pixel values of the encoded image, but complex photographic content may create a larger file than a lossy format.
PNG is not inherently “higher quality” for every purpose; the right choice depends on whether exact edges, transparency, editing, or compact photographic delivery matters most.
WebP: a modern web option
WebP supports both lossy and lossless encoding and can preserve transparency. It is supported by current browsers, but older software or a specific publishing workflow may still require a fallback format.
WebP output size and appearance depend on the source and encoder settings. Compare it at the expected display size and check that your destination accepts it.
Compare formats with Pixuna
Open the Image Converter, choose an image, and select JPEG, PNG, or WebP as the output. The browser performs image conversion; actual output encoding depends on browser support, so inspect the resulting file rather than relying only on its extension.
If you are optimizing an image for a website, also resize oversized source images and keep the original file. Pixuna’s image tools run in the browser.