JPG for many photographs
JPG is widely compatible and uses lossy compression. It works well for detailed photographs and web uploads where a smaller file matters. It does not preserve alpha transparency, so transparent backgrounds turn white on export.
PNG for graphics and transparency
PNG stores pixels without JPEG-style artifacts and supports alpha transparency. Logos, interface captures and text-heavy graphics often look better in PNG, although large photo PNGs can be much heavier than JPG.
WebP for modern web publishing
WebP supports compact files and transparent pixels. Most modern browsers support it, but some older or specialized software may still ask for JPG or PNG.
Conversion is not upscaling
Switching a small JPG to PNG does not restore lost detail or make it sharp. It changes how existing pixels are stored. Use the image format converter or a dedicated format page when a form requires a specific format.