Which format should I use?
WebP is the default answer for the web. It is roughly 25 to 35 percent smaller than JPEG at the same visual quality, supports transparency, and every current browser reads it.
JPEG is the safe choice for photos that need to open anywhere, including old software and print shops. No transparency.
PNG is for graphics with sharp edges, screenshots, logos and anything that needs transparency. Lossless, so files get large quickly for photographs.
Typical conversions
- PNG to WebP or PNG to JPEG: the biggest win. Screenshots saved as PNG often shrink by 80 percent or more.
- JPEG to WebP: a solid 25 to 35 percent saving for website images.
- WebP to JPEG: when a tool or printer refuses WebP.
- HEIC from an iPhone: not supported here, because browsers cannot decode it. Set your iPhone to “Most Compatible” under Settings, Camera, Formats, and it will produce JPEG instead.
Quality settings
For WebP and JPEG the quality slider controls compression. 85 is a good default. Going to 100 roughly doubles the file size for a difference you will not see on screen.
When converting a transparent PNG to JPEG, transparency has to be replaced by a solid colour. Pick that colour above, white by default.
Questions
Is the conversion lossless?
Converting to PNG is lossless. WebP and JPEG use lossy compression at the quality you choose. Converting a JPEG to PNG does not restore quality that was already lost.
Can I convert HEIC files from my iPhone?
No. Browsers cannot decode HEIC. Change your iPhone to Most Compatible under Settings, Camera, Formats to get JPEG files instead.
How many files at once?
Up to 30 per batch. They all use the same settings.
Does converting reduce quality every time?
Each lossy re-encode loses a little. Convert from the original whenever possible instead of chaining conversions.