Compress Image - Reduce File Size, Keep Quality

For JPEG, going from 100% to 80% quality typically reduces file size by 50–70% with virtually no visible difference on screen or print. For PNG with flat colors, switching to WebP lossless can reduce size by 25–35%. The right quality depends on your use case - web thumbnails can use 60–70% quality; print assets should stay at 85–95%.

JPEG, WebP and AVIF compress by approximating detail, so lowering quality trades sharpness for size. PNG stores pixels exactly, so this tool compresses it by reducing the number of colours to at most 256, with dithering to keep gradients smooth. A screenshot usually drops 70–90% that way; at 95% quality and above the PNG stays lossless.

Yes, re-compressing JPEG introduces "generation loss" - each compression cycle degrades quality slightly. This tool minimizes damage by using a high-quality decoder (jsquash), but the principle applies. If preserving maximum quality is critical, compress from the original RAW or lossless source, not from an already-compressed JPEG.

Because the slider sets how much detail is kept, not a target size. At the same setting, a camera original might lose 80% and a copy that was already compressed only 25%, since it has less left to remove. If a file would come out bigger, the original is kept instead, so lower the quality to shrink it further.

Standard JPEG compression is inherently lossy. There are lossless JPEG optimization tools (like jpegtran) that strip metadata and optimize Huffman coding without touching pixels - typically saving 2–8%. This tool uses lossy re-encoding at your chosen quality. For lossless JPEG optimization, consider ImageOptim on macOS or Squoosh with its Mozjpeg encoder at 100% quality.