Compress images to a target size

How the target size works

Upload forms ask for a photo under 100 KB or 2 MB, not for a quality setting, so the default goal is a size. The compressor first tries the photo at quality 95; if that already fits, you get it. Otherwise it searches for the highest quality between 45 and 95 that stays under the limit. Only when even quality 45 is too big does it make the picture smaller in pixels and search again. Below about 45, JPG starts to show its 8 pixel blocks, and a smaller picture at a decent quality looks better than a full size one that is blocky.

We gave it six photos straight from cameras and phones:

What decides the result is how much detail a photo holds, not how big its file was. The smooth sunset fitted under 100 KB at full size, while the lake, full of leaves and ripples, had to drop to about 1,200 pixels wide. That is still more than a passport form or a profile picture needs. If a form asks for exact pixel dimensions as well, set them first with resize image.

The Quality goal

Choose Quality to compress by a setting instead of a size; the default is 80. At 80 the cat went from 2.62 MB to 361 KB and the coffee photo from 15.5 MB to 1.74 MB. The macaw did the opposite: its camera had already saved it compactly, and quality 80 made it 2.03 MB, larger than the 1.87 MB original. When that happens, the compressor keeps the original and tells you so. Which JPEG quality setting should you use shows what each step of the scale changes.

Choosing the format

• Each file's own, the default, keeps JPG as JPG and PNG as PNG, so nothing changes for whoever receives the file.
• WebP makes smaller files than JPG at the same look and opens in every current browser, but some forms and older programs refuse it.
• AVIF is smaller still on most photos and the slowest to encode. Use it for websites, not for forms.
• PNG suits screenshots, logos and graphics. With fewer colours and dithering, the compressor shrinks them a lot while keeping text sharp.

Lossless

The Lossless goal changes the file without changing the picture where the format allows it. PNG is repacked by OxiPNG and stays identical pixel for pixel; WebP uses its lossless mode. JPG cannot be repacked that way, so it is saved again at quality 95, which looks the same but is not bit for bit identical. Whenever a new file is written, the photo's metadata, including its location, is left out.

If something goes wrong

• It says it could not reach the target. The limit is very small for this picture. Raise the target, or choose a smaller longest side so the search starts from fewer pixels.
• It is slow. Each target search encodes the photo several times. Large camera photos took 7 to 65 seconds each in our test; capping the longest side at 2560 or 1920 pixels makes it much faster.
• Text in a screenshot looks smudged. Choose PNG as the format, or set a quality of 90 or more.

How we tested. Six CC0 photos from Unsplash via Wikimedia Commons, as published, between 1.9 and 22.8 MB. Each was compressed as JPG with the tool's own code in Chrome to 100, 200 and 500 KB targets, and at quality 80.