Use JPEG for broad photo compatibility
JPEG is dependable for photographs and supported almost everywhere, but it loses transparency and accumulates artifacts after repeated saves.
Use PNG for exact edges and alpha
PNG is lossless and well suited to UI captures, line art, and transparent assets, though photographs can become large.
Use WebP when the destination accepts it
WebP supports both lossy and lossless encoding plus alpha. It often reduces bytes, but some upload portals still reject it.
Compare a real output
Export the same source in candidate formats and inspect the important regions at 100% zoom. Choose using the receiving system, not a theoretical ranking.
Match format to image structure
Photographs contain gradual color changes and irregular detail that lossy encoders can simplify, while interface captures, diagrams, and small type expose ringing and blur quickly. Transparency adds another constraint: JPEG requires a fixed background, whereas PNG and WebP can retain alpha. Classify the source before looking at file size. A larger PNG may be the safer choice for a crisp instructional screenshot, and a JPEG may be the practical choice for a fully opaque photo even when both files render in the browser.
Verify decode and upload behavior
A browser successfully creating a file does not prove that a CMS, email client, print workflow, or legacy upload form accepts it. Test one output in the exact destination before converting a whole batch. Confirm orientation, transparency, dimensions, and color on the destination, then inspect the downloaded or published copy if the service transforms images again. When a system rejects WebP, regenerate JPEG or PNG from the original source rather than transcoding the WebP derivative. Preserve originals because this local converter intentionally discards metadata and does not manage print color profiles.