format conversion
PNG to WebP
The one pair here where the smaller file does not cost you anything the source was using: WebP carries the alpha channel PNG carries.
What actually changes
83,298 B against 133,198 B, same pixels
Measured in this repo on one file, written as a lossless WebP and as a PNG. Nothing was given up between the two — the difference is the encoder. That measurement is why the image compressor exists as a separate tool rather than as a dial on this one.
Source src/lib/seo/registry.ts — the image-compressor entry
Transparency survives
Both formats carry an alpha channel, so this is the conversion out of PNG that changes nothing about what the image can express.
Source The converter’s own format notes — src/copy/en/convert.ts
The converter’s WebP is lossy by default
The number above is a lossless WebP. Here the quality dial reaches WebP, so the file you download is smaller again and has given something up. One dial serves both JPEG and WebP on purpose: three sizes are only comparable if they were asked for the same thing.
Source The quality control’s own note — src/copy/en/convert.ts
An already-optimised PNG can come back larger
PNG is lossless, so re-encoding one cannot beat a tool written to squeeze it. If your PNG has already been through such a tool, the PNG column in the results table may be bigger than the file you dropped in. The WebP column is the one to read.
Source The note under the results table — src/copy/en/convert.ts
The short answer
The default answer for a PNG going onto a web page. Keep the PNG if something downstream will not read WebP.
Convert it here
The converter takes your file, writes it as PNG, JPEG and WebP at the same pixel size, and shows you what each one weighs — measured on your file rather than on an average. It runs on the page using WebAssembly; the image never leaves your device.
Open the image converterThe other conversions
Every pair this tool can actually do. There are nine because it reads four formats and writes three, and a format cannot be converted to itself.
This page carries 4 facts and a source for each one. It is one of nine, generated from the same list the converter reads — so a page cannot exist here for a format the file picker would refuse.