How to compress an image without losing quality

Lossy vs lossless, in plain terms

There are two ways to make an image smaller. Knowing which one you are using tells you what to expect.

For a photo, well-tuned lossy compression at around 75–85% quality is usually indistinguishable from the original at a fraction of the size. The visible damage only appears when you push quality very low or re-save the same JPG over and over.

Pick the right format first

Choosing the wrong format is the most common reason a file is needlessly huge. Match the format to the content.

Resize before you compress (the step people skip)

A photo straight off a phone can be 4000 pixels wide, far more than any website, form or print needs. Compressing a giant image fights a losing battle. Cut the pixel dimensions to what you actually need first, and the file shrinks dramatically before the compressor does anything.

If a thumbnail only displays at 600 pixels, resize it to 600 pixels, then compress. The smaller pixel count means the compressor can keep higher quality per pixel, so you end up with a smaller and sharper file than if you had only compressed the original.

Hit an exact KB target for forms

Upload forms rarely ask for a quality percentage. They ask for a file under a fixed KB ceiling, and guessing the quality slider to land on "under 50 KB" is tedious. The compress to KB tool takes the target number directly and finds the quality for you.

• Aim just under the maximum (for example 48 KB on a 50 KB cap) so a portal re-save does not push you over.
• If compression drops the file below a stated minimum, pad it back up without changing how it looks.
• Compressing many files for the same limit? Do them in one pass with the bulk compressor.