Image Compressor

Where the size actually goes

Two things dominate image file size: pixel dimensions and compression quality. Resizing a 4000-pixel-wide photograph to the 800 pixels it is actually displayed at removes roughly 96 percent of the data before any compression is applied. Compressing without resizing first is optimising the smaller of the two factors.

Quality 80 is the sweet spot

For JPEG and WebP, quality around 80 is where the curve bends. The difference from 100 is invisible in normal viewing while the file is a fraction of the size. Above 90 the file grows steeply for gains nobody can see. Below about 60, artefacts become visible in smooth gradients and around sharp edges, most noticeably in skies and text.

Lossy and lossless are different tools

JPEG and lossy WebP discard information permanently to achieve large reductions, which is correct for photographs where the eye cannot detect the loss. PNG and lossless WebP preserve every pixel, which is correct for screenshots, logos and anything with sharp edges or text, where lossy compression produces visible fringing. Using PNG for a photograph typically produces a file several times larger than necessary; using JPEG for a screenshot makes the text look dirty.

Re-compressing compounds loss

Every lossy save discards more information, and it never comes back. Editing a JPEG and re-saving repeatedly degrades it visibly over a few generations. Always compress from the original, not from a previously exported copy, and keep the original somewhere.

Format choice beats compression settings

Converting a JPEG to WebP at equivalent visual quality typically saves 25 to 35 percent. AVIF often halves it again, at the cost of slower encoding and slightly narrower support. For a site where images dominate page weight, changing format achieves more than tuning quality on the existing one.

Processed on your device

Compression uses the browser canvas, so files never leave your machine. Canvas processing also strips EXIF metadata including GPS coordinates, which is usually what you want before publishing a photograph.