Image to WebP Converter

How the Image To WebP works

Image to WebP: what to know first

WebP is the format worth converting to for almost everything on the web. It supports both lossy and lossless compression, alpha transparency in both modes, and animation, and it typically lands twenty to thirty per cent smaller than a JPEG of equivalent visual quality. Every current browser reads it, which removed the last real reason to stay on JPEG for photographs and PNG for graphics with transparency.

Lossy versus lossless is the choice that matters. JPEG and lossy WebP throw information away and keep throwing it away every time you re-save, which is why a photo that has been edited and saved half a dozen times looks soft and blocky. PNG and lossless WebP keep everything, at the cost of a much larger file for photographic content. The rule of thumb that holds up: photographs go lossy, anything with flat colour, hard edges or text — screenshots, logos, diagrams, UI mockups — goes lossless, because lossy compression puts visible fringes around exactly those edges.

What the quality number actually means. It is not a percentage of anything. It is a knob on the quantisation tables the encoder uses, and the relationship between the number and the file size is steeply non-linear. Going from 100 to 90 typically halves the file with no visible difference at all; 90 to 80 saves a little more and is still hard to spot; below about 60 the artefacts become obvious in flat areas like skies. For WebP, 75 to 85 is the range most sites settle on. PNG ignores the slider entirely, because there is nothing to trade.

Resizing beats compressing. If an image is 4000 pixels wide and will be displayed 800 pixels wide, no amount of quality tuning matters next to simply making it smaller: file size scales with the pixel count, so halving the width quarters the data. Set a maximum width that matches the largest size the image will actually be shown at, then double it if you are serving high-density screens. That single step usually does more than every other optimisation combined.

Converting to JPEG loses transparency. JPEG has no alpha channel, so a transparent PNG converted to JPEG has to be composited onto something. This tool fills the background white, which is the conventional choice and the least surprising result, but if your image will sit on a dark page you want WebP or PNG instead.

Metadata does not survive. The conversion decodes the picture and re-encodes it from pixels, so EXIF, GPS coordinates and colour profiles are not carried over. That is a privacy win, and it is also a caveat: if you need the metadata preserved, convert somewhere else, and if you want the metadata gone but the compression untouched, strip it instead of converting.

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