PNG to WebP on Mac
This is the one direction macOS leaves out. Finder's Convert Image quick action writes JPEG, PNG, or HEIF and nothing else. Preview's Export dialog goes further, to JPEG, JPEG 2000, PDF, PNG, and TIFF, plus HEIC and OpenEXR with the Option key held, and WebP is still not on the list. Press writes WebP through libwebp: lossless when the quality slider is at 100, lossy below that, with the PNG's transparency carried across.
- Drop the PNG files onto Press.
- Under Image, choose WebP. Leave Quality at 100 for a lossless file, or lower it for a smaller lossy one; 80 to 85 suits photos.
- Click Convert. Each file is written as name (Press).webp beside the source.
What you get
- Container
- A .webp next to the PNG.
- Codec
- WebP through libwebp. 100 percent uses the lossless encoder; anything lower uses the lossy one at that quality.
- Quality
- At 100 the pixels are identical to the PNG. Below that, WebP's lossy mode discards detail the way JPEG does, at a smaller size for the same look.
- Metadata
- PNG carries little metadata and none of it is copied. Press writes WebP without an embedded color profile.
Is the WebP really lossless at 100?
Yes. At 100 percent Press calls libwebp's lossless encoder rather than the lossy one at its top setting, so the decoded pixels match the PNG exactly.
Does transparency survive?
Yes. Press un-premultiplies the alpha channel before encoding, so soft edges keep their color instead of darkening.
Why is WebP output a Pro feature?
WebP, AVIF, and TIFF output, batch conversion, size presets, and downscaling are the Press Pro set, a one-time unlock priced on the Press page. JPEG, PNG, and HEIC output are free.
Press converts video and images on your Mac. The download is free, and Press Pro is a one-time $14.99 unlock for batch conversion, size presets, and WebP.