JPG vs PNG

The compression difference, demystified. JPG uses Discrete Cosine Transform (DCT) — it converts 8×8 pixel blocks into frequency components, then discards high-frequency data your visual system barely registers. At quality 85, you typically lose 80–95% of the file size with negligible perceptual loss in photos. The catch: each save re-applies the lossy step, so editing a JPG and re-saving 10 times leaves visible blur and color shifts ("generation loss").

PNG uses DEFLATE (the same algorithm as ZIP) — it never discards data, only compresses redundant patterns. A flat-color logo with 4 colors might compress 50:1; a noisy photo only 1.5:1, which is why photos in PNG balloon to 5–10× the JPG size. PNG also supports an alpha channel (transparency), which JPG fundamentally cannot: a JPG either has a white background or whatever color the encoder chose.

When transparency forces your hand. If you need anti-aliased edges over a non-white background — UI icons, web mockups, marketing graphics — PNG is mandatory. JPG will fill the alpha with white and create ugly halos. Modern formats like WebP and AVIF combine the best of both (lossy/lossless modes + alpha), and we recommend trying JPG → WebP or PNG → WebP for ~30–50% smaller files at equivalent quality.

The 2026 verdict. For 90% of web work: JPG for photos at quality 80–85, PNG for everything with transparency or hard edges. For the bleeding edge: WebP for both, with JPG/PNG fallback via <picture>. Avoid PNG-24 for photos (massive files) and avoid JPG for anything you'll re-edit.