First, an honest word about "lossless"

JPG is a lossy format by design — so "shrink a JPG completely losslessly" is mostly a myth. What's realistic and what people actually mean is: make it much smaller while it still looks identical to the eye. And that's very achievable, because the human eye barely notices the information JPG discards. Two levers do the work.

Lever 1: reduce the dimensions

The single biggest win. If a photo is 4000 pixels wide but displayed at 800, those extra pixels are pure weight. File size grows with area, so halving the width roughly quarters the data. For web use, 1600–2000 px on the long edge is plenty; for a chat, even less. Resize with the resize tool before anything else — often this alone shrinks a photo by 80% with no visible change.

Lever 2: lower the quality — but not too far

The quality setting decides how aggressively JPG discards detail. The key insight: the curve isn't linear.

  • 100 → 90: barely any visible difference, often already half the size.
  • 90 → 80: still hard to notice, more savings.
  • 80 → 60: you start to look closer; for photos often still fine.
  • below 50: artifacts become obvious, and each step saves less.

In other words, the most expensive bytes of an image are in the last few percent of quality almost no one sees. That's why quality 80 is the sweet spot: it looks essentially perfect on screen while the file is already much smaller.

The mistake to avoid: re-saving repeatedly

Because JPG is lossy, every re-save adds artifacts. Open, tweak, save, repeat — and the photo degrades round after round. So: start from the original, resize once, compress once, done. Never edit a JPG that's already been through several save cycles if you can start from the source instead.

How to do it — browser-locally

Drop the photo into the JPG compression tool, set the quality (start at 80), and download — the size drops live in the preview, and the file isn't uploaded anywhere. For the biggest effect, resize first, then compress.

The short version

  • Resize to the size you actually need — the biggest lever.
  • Compress at quality ~80 — invisible loss, big savings.
  • Do each once, starting from the original.
  • Forget "truly lossless" — aim for "looks identical", which is what you really want.