Image Compressor

This compressor re-encodes your image as a JPEG at a quality level you control with the slider, then reports the size difference immediately. JPEG is a lossy format: it throws away image detail the human eye is less sensitive to — subtle color gradients and high-frequency texture — in exchange for a smaller file. At 100% quality very little is discarded and the file stays close to the original size; drag the slider down toward 60-70% and the encoder gets more aggressive about approximating blocks of pixels, which is where most of the size savings come from before artifacts become visible.

Under the hood, the image is drawn onto an HTML canvas and re-exported through the browser's built-in JPEG encoder (canvas.toBlob), so there's no upload step and no server-side processing queue — the trade-off happens instantly as you drag the slider. This also means the output is always a JPEG, even if you upload a PNG, since JPEG is what makes the quality/size trade-off adjustable in the first place.

Because compression is lossy, it's a one-way operation — re-compressing an already-compressed JPEG at a lower quality compounds artifacting rather than reversing it. For images with sharp edges, transparency, or flat colors like logos and screenshots, a lossless format or an SVG will usually hold up better than pushing the quality slider down.

JPEG is a lossy format. It divides the image into 8x8 pixel blocks, then discards fine detail the eye is less sensitive to. Lower quality discards more, so the file shrinks but artifacts increase.

The output is re-encoded as JPEG, so transparency in PNG files is lost and flattened. Re-compressing an already-compressed JPEG compounds the loss, so always work from the original file, not a previous export.