Compress Image to 100KB

100 KB is one of the most common file size limits, usually for a practical reason:

• Upload forms. Application forms, booking systems and support portals receive thousands of photos, so they limit each one to keep storage manageable.
• Email signatures. A logo or headshot embedded in your signature is sent again with every message you write.
• Web pages. Images are usually the heaviest part of a page, and keeping a large photo to around 100 KB helps it load quickly on mobile data.

This tool counts a kilobyte as 1,024 bytes, so a 100 KB result can be up to 102,400 bytes. Some forms count 1,000. If you can’t tell which, enter 97: 97 × 1,024 is 99,328 bytes, under the limit either way.

We compressed four photos with this page’s settings. All four came back under 100 KB as JPGs at 64% quality, with fewer pixels:

How many pixels survive depends on detail, not on the original size: plain sky and walls cost little, while food, leaves and hair cost a lot. At the size a screen shows them, the smaller versions look clean; zoomed right in they’re softer, but not blocky.

Lowering the quality only goes so far. At very low settings, JPG photos break into small square blocks, and smooth areas such as sky turn into visible bands of colour.

With Make images smaller if needed ticked, the compressor never goes below 60%. If a photo still won’t fit, it’s saved with fewer pixels, scaled from the full-size original with its shape unchanged, and the result says Made smaller to fit with the new size. Photos that fit at 60% or better keep every pixel, and one already under 100 KB is never made smaller.

Untick the box and every pixel is kept, but quality can fall as low as 5%. Our lake photo reached 95.5 KB at full size that way, at 7% quality, and its sky broke into stripes you could see without zooming in. The food photo couldn’t get under 100 KB at all: it was still 124.6 KB at 5%.

Keep Same as original for forms: JPGs stay JPGs, which every form accepts, and iPhone photos come out as JPG too.

Choose Smallest file for your own website, or a form that accepts WebP. At the same 100 KB, WebP kept 30% to 80% more pixels than JPG in our tests.

PNG is the exception. It’s lossless, so with Same as original the only way to 100 KB is fewer pixels: a 1600 × 1280 photo saved as PNG came back 220 × 176. Choose Smallest file for PNG photos (that one became an 846 × 677 WebP). Safari can’t save WebP, so there, convert them with PNG to JPG first. The 50 KB page has more on PNGs and transparency.

Some forms and website themes ask for a size in pixels too. Resize the photo to it first, then compress it here with Make images smaller if needed unticked, so only the quality changes.