A good size for most uploads
One hundred kilobytes is large enough for a clean picture and small enough for almost every upload limit. A photo around 1,100 pixels wide fits when the quality is chosen well, and a smooth image fits even larger. That makes 100 KB a practical default for profile photos, product pictures and anything that will be shown on a screen rather than printed.
The tool starts from the highest quality it is allowed to use and goes down until the file fits, so you get the best picture that 100 KB can hold, not just any picture under 100 KB. If a picture is large, noisy or full of fine texture, it may also need to be made smaller in pixels. The result then says what the new size is.
Quality versus pixels at 100 KB
- A 4,000 pixel wide photo cannot keep all its pixels in 100 KB. When we compared the ways of reaching 100 KB, a picture about a third of the original width at a medium quality looked better than the full size at a very low quality, so that is what the tool aims for.
- Photos saved as PNG are many times bigger than they need to be. Choose JPG or WebP under Format for a much better result at 100 KB.
- Scans of documents need enough pixels for small text. Scan at a modest resolution, then compress from the original rather than from a smaller copy.
To pick the size yourself, set the longest side before compressing, or use Resize Image.
A budget for web pages
Most of a web page's weight is its pictures, and 100 KB is a common budget for one content picture: ten of them are a megabyte, which loads quickly even on a mobile connection. If you serve your own site, saving as WebP can fit more quality into the same 100 KB. In our tests WebP at the same similarity score was between 4 percent smaller than JPG, for a detailed photo, and 45 percent smaller, for small or smooth pictures, so try both and look at them in the compare view.
A repeatable workflow for a folder of pictures
- Drag the whole folder in. Small pictures are processed several at a time and large ones one after another.
- Leave Format on Same, or choose WebP for your site.
- Add a Largest side if every picture only needs to be, say, 1,600 pixels wide. Fewer pixels is the biggest saving of all.
- Download the ZIP. A compressed copy gets "-compressed" added to its name, so your originals are never overwritten. A picture that came back unchanged because it was already small enough keeps its own name.
- Open the compare view on the heaviest few to check text and faces.
Reading the result
The list shows the quality chosen for each picture, how much of the 100 KB limit it used, and, when a picture had to be made smaller to fit, its new pixel size. A picture that already fits 100 KB at the Balanced level is returned at that result rather than stretched up to the limit, so file sizes vary, and some are far below it. A picture that is already smaller than 100 KB and as compact as it can be comes back unchanged.