Compress an image to under 500KB

Reduce dimensions first

500 KB is a common ceiling on job application portals, government forms, forum attachments and older content systems, and the instinct is to drag the quality slider down until the number fits. That produces a large, visibly damaged image.

File size scales with pixel count, so resizing is the more powerful lever. A 4000-pixel photo dropped to 1600 pixels is roughly a sixth of the data before quality is touched at all — usually enough on its own, with no perceptible loss, because nothing displaying it needed 4000 pixels.

A reliable order of operations

Work through these in order and stop as soon as you are under the limit:

• Resize to the largest dimension the image will actually be shown at — often 1600 pixels or less.
• Export at quality 80–85, which is visually indistinguishable from the original on most photographs.
• Switch format if the destination allows it: WebP is typically 25–35% smaller than JPG at matched quality.
• Only then lower quality further, and check the result at full size before accepting it.

When the file will not shrink

Some images resist compression for structural reasons. Screenshots and images containing text have sharp edges that lossy compression handles badly, so they stay large at any acceptable quality — convert those to PNG, which often ends up smaller than a high-quality JPG of the same content.

Photographs with large smooth gradients, like clear skies, band visibly before they get small. And a PNG of a photograph is the classic case: it is likely five to ten times larger than it needs to be purely because of the format, and converting to JPG or WebP will collapse it.