Image Compressor

Resize before you compress

Pixel dimensions decide most of a file's weight. A phone photo is often 4000 pixels wide, while a page rarely shows it wider than 1600–2000, so resizing first removes most of the bytes before any quality is traded away. A photo at a quarter of the pixels is roughly a quarter of the size at the same quality setting.

Choosing a quality setting

For JPG and WebP, a quality between 75 and 85 is usually indistinguishable from the original on screen and far smaller. Below about 60, blocky patches appear in skies and smooth skin, and halos appear around edges. PNG ignores the slider because it is lossless; it gets smaller only by having fewer pixels or fewer colours.

If the result shows faint rings around text or blotches in dark areas, raise the quality a step rather than resizing further; those artifacts are the encoder running out of bits, and they are most visible on screenshots saved as JPG.

Match the format to the picture

Photographs compress best as WebP or JPG. Screenshots, diagrams, and anything with text or flat colour stay sharper as PNG or high-quality WebP, because JPG smears the edges of letters. To change format as part of the job, use JPG to WebP or PNG to JPG.

As a working target, a full-width photo on a web page is comfortable under about 300 KB and an image inside an article under about 150 KB; anything much larger slows the page on a phone connection.

Compressing to a size limit

When a form or an email sets a maximum, choose a target size instead of a quality. The compressor tries the highest quality first and bisects down until the file fits, so the result is as sharp as the limit allows rather than as small as possible. If even about 50% quality is too big at full size, it scales the picture down and searches again, because fewer pixels at a decent quality look better than full size at a quality low enough to show blocks.

The limit is read as 1,000 bytes per KB, the stricter of the two ways a site can count, so a file made for 100 KB passes a check of 100,000 or 102,400 bytes. PNG cannot be steered to a size because it is lossless, so a target always produces a JPG or WebP. For the common case there is a page already set up: compress an image to 100 KB.

How to use it

1. Drop an image or choose one from your device.
2. Set the output format and quality.
3. Compress, compare the file size, and download the result.

Privacy & limitations

The file never leaves your browser. Canvas export may remove embedded metadata, and PNG quality is lossless rather than controlled by the quality slider.