WebP vs PNG: compare actual file sizes
Measure PNG and WebP output sizes from your own image in your browser. Compare detail, transparency and compatibility before choosing a format.
Prepared by UrlToFile Dev · October 15, 2026.
There is no fixed percentage that WebP will save on every image. A photograph, flat logo and transparent screenshot contain different kinds of detail. Measure the image you intend to use rather than multiplying its size by an advertised compression ratio.
Measure your own image.
Create PNG and WebP copies at the same dimensions, then compare their actual encoded sizes. Nothing is uploaded.
Up to 20 MB and 16 megapixels. Animated inputs are unsupported. Metadata is not preserved. The input file stays unchanged.
Choose an image to start.
What this comparison measures
Both outputs use the same decoded pixels and dimensions. PNG uses lossless compression. WebP uses the selected lossy quality setting, so a smaller file may contain less detail. The tool reports the bytes of the generated files, not an estimate. It compares those two new outputs, not either output against your original upload. Browser encoders can produce different sizes.
Choose PNG when exact pixel values matter
PNG is a useful starting point for screenshots with small text, diagrams and graphics that need transparency. Converting a JPEG photograph into PNG does not restore detail the JPEG already lost. It may produce a much larger file. Check the receiving system accepts PNG and whether its upload limit is measured in bytes or rounded megabytes.
Choose WebP when size matters and the destination accepts it
WebP can be useful for website photographs and transparent graphics. Inspect text edges, fine patterns and gradients at the size people will actually see. Raising quality can reduce visible artifacts while increasing file size. Some forms still require JPEG or PNG, so compatibility comes before savings.
Resize before chasing a smaller percentage
A 4000-pixel photograph used in a 600-pixel slot may contain unnecessary pixels. Use Resize images, then return to compare the reduced copy. For several files, use batch image compression or image format conversion. Keep the original and verify each saved output.
Privacy and limits
This comparison reads and encodes one local image without uploading it. It accepts still JPG, PNG and WebP up to 20 MB and 16 megapixels. Animation and metadata are not preserved. Cancel invalidates pending results; closing the page releases the generated copies. Browser downloads remain yours to manage.
For a complete upload task, see meet an image upload limit.