How the tool reaches an exact size
Compression here is a search, not a slider. For JPEG and WebP the tool encodes your image at a series of quality levels and keeps the highest one whose file still fits under your cap — the same divide-and-consume logic a binary search uses. That is why the result lands just under the target instead of far below it.
When even the lowest sensible quality overshoots the cap, the tool scales the pixels down and searches again, and the result line tells you it did. A smaller image at reasonable quality almost always looks better than a full-size one ground into mush, which is why scaling is the fallback rather than pushing quality to zero.
Why a 20 KB photo looks the way it does
A file size is a budget for information. A modern phone photo carries several megabytes of detail; a form demanding 20 KB is asking you to spend about a thousandth of that. Something has to give, and the only choices are blur (compression artifacts), fewer pixels, or both.
This is worth knowing before you blame the tool: a 4000-pixel-wide photo squeezed to 20 KB cannot look sharp, because sharpness is exactly the information the budget cannot hold. For document and passport photos the result is usually fine, since a face at web resolution survives compression well. For a detailed screenshot or a photo of small text, aim for the largest cap the form accepts.
Kilobytes and pixels are different problems
Forms and portals cap the file size in KB or MB, because that is what their storage costs. Screens and layouts care about dimensions in pixels. If you need specific dimensions — a square crop for a profile, 1080 pixels for a post — use the image resizer. If you need a different format, the image converter shows the saving per format. This tool is for the third case: the same picture, fewer bytes, dimensions untouched wherever possible.
Why nothing is uploaded
The file people compress for a size cap is usually their least anonymous one: a passport photo, a signature, a scan of an ID for a housing or visa portal. On an upload-based compressor that file travels to a server you know nothing about, and the promise to delete it is a sentence on a page, not something you can check.
Here the work happens in your browser with the standard canvas API. There is no upload, no queue and no file size limit beyond your device’s memory, and you can watch the network tab while you use it: no request carries your photo. More on the difference in why upload-based tools are a privacy problem.
Questions
How exact is the target size?
The result is always at or under the target, usually within a few percent of it. The tool keeps the highest quality that fits, so it does not go far below the cap on purpose.
Does compressing change my image's dimensions?
Only when the target cannot be met with quality alone. Then the pixels are scaled down and the result line says so. You never get a silent resize.
What happens with PNG and transparency?
PNG has no quality setting, so a PNG target is reached by reducing dimensions. Choosing JPEG or WebP as the output format usually keeps more pixels. Transparency survives in PNG and WebP; in JPEG it becomes white.
Is my photo uploaded anywhere?
No. The compression runs in your browser with the canvas API. Your photo never leaves your device, and you can verify it in your browser's network tab — no request carries it.