Compress WebP Images

Why a WebP file is often larger than it needs to be

WebP files come out of cameras, design apps, screenshots, and downloads, and each of those saves at a different quality. A designer exporting a hero image at maximum quality, a phone saving a photo, and a screenshot utility will all produce very different file sizes for the same kind of picture. Most of them are far above what a screen actually needs, which is where the savings come from.

NoteThese are indicative ranges for a typical photograph. A detailed landscape and a flat graphic at the same quality can differ by a factor of two or more.

The re-encoding trade-off nobody mentions

Compressing a lossy format is not the same as compressing a file. A JPG or WebP has already thrown information away, and running it through the encoder again throws away a bit more. The result is usually fine for screen use, which is why this is worth doing, but it is not free and it is not reversible. The sensible pattern is to compress once, from the original, and keep the original.

• Always compress from the original, never from a file you already compressed.
• The file size and quality are shown together so you can judge the trade rather than guess.
• Keep the original. If you need a different quality later, go back to it instead of re-compressing the output.
• If the image will be printed or edited later, do not compress it now.

Choosing a quality setting that suits the image

There is no single right setting, because the acceptable quality depends on the content and the display size. A detailed landscape with foliage and texture shows compression artefacts much earlier than a flat graphic or a portrait against a plain background. If you are unsure, compare the two versions at 100 percent and decide from that rather than from a preset name.

• Start at balanced for a general website image.
• Move up one step for images with fine detail, text, or gradients.
• Move down only when the file size is the real constraint, such as on a slow connection.
• Check the result at 100 percent. Compression artefacts are invisible at normal viewing distance and obvious when zoomed.

When a different tool is the better answer

Compression is the right tool when the format is correct and only the file size is too large. It is the wrong tool when the file needs to be smaller for a structural reason, such as a full resolution photo being used as a thumbnail. Converting to a more efficient format, or resizing to the dimensions actually displayed, usually gives more for the same effort.

• File too big, format fine: compress it, which is what this page does.
• File needs to be much smaller: convert to AVIF, which compresses more efficiently at the same quality.
• Image is far larger than where it displays: resize it first, then compress.
• You need an exact byte limit: use a target size compressor.