Compress an image to a target size

A quality slider does not answer the question people actually have, which is whether the file is under the limit a form will accept. This tool works backwards from that limit instead.

It re-encodes the image at a quality level, measures the bytes that came out, and bisects: too big means try lower, small enough means try a little higher to keep as much quality as the target allows. Seven passes gets within about one percent of the best quality that fits.

Only when the lowest usable quality still misses does it start scaling the image down, in steps, retrying the quality search at each one. That order is deliberate. Somebody who needs a photo under 100 KB wants the same photo smaller, not a thumbnail.

Every image has a floor. A 12 megapixel photo will not become a readable 20 KB JPG, no matter how the compressor is asked. When the floor is above your target, this tool says so and hands you the smallest version it managed, with the size it reached, rather than pretending it succeeded.

Two things usually fix it. Switch the output to WebP, which is typically smaller than JPG at the same visual quality. Or accept a smaller pixel size, since an image being uploaded to a form rarely needs to stay at full camera resolution.

Exam and government portals in particular are strict, and the limits are usually written into the form itself: photographs often have to fit in 20 to 100 KB, signatures in 10 to 20 KB, and supporting documents in 200 KB to 2 MB. Read the limit off your form and type it in rather than guessing.

For the web, the useful rule is different: aim for the smallest file that still looks right at the size it is displayed. A hero image at 200 KB and a thumbnail at 20 KB is a reasonable place to start.

How do I compress an image to a specific file size?

Set the target size, for example 100 KB, and the tool re-encodes the image at descending quality levels until the result lands under your target. It reports the exact size it reached, so you can see how much margin you have.

What if the target size cannot be reached?

The tool tells you plainly instead of returning a broken file. If quality alone is not enough, it scales the image down in steps and tries again, and if even that misses, it hands you the smallest version it managed along with the size it reached.

Does compressing an image reduce its dimensions?

Only if it has to. Quality is reduced first, which keeps the pixel dimensions intact. Downscaling starts only when the smallest usable quality still misses the target.

Is the compression lossless?

No. Hitting a target size means discarding image data, which is why the preview shows the compressed result next to the original at full size. Zoom in on text and sharp edges, since that is where the loss shows first.

Which format compresses the smallest?

WebP is usually the smallest for the same visual quality, and JPG is close behind with wider support in older software. PNG is lossless, so it is a poor choice when you are chasing a size target on a photograph.

Do my files get uploaded anywhere?

No. Compression runs entirely in your browser, so the image never leaves your device and nothing is stored.