Image Compressor

How Image Compressor works

Compress images in your browser with quality control and a live before/after size preview. No uploads. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

Two levers, one goal

File size comes down two ways: fewer pixels, or fewer bits per pixel. The quality slider handles the second, the maximum-edge field handles the first. For a photo straight off a phone, shrinking the long edge to 1600 px usually saves more than any quality setting, and looks better too.

The tool shows the original and compressed size side by side, with the saving as a percentage, so you can stop turning the dial once the number stops improving.

What quality actually means per format

For JPG and WebP, quality is a compression target, not a fixed bitrate. The same 78% can produce very different file sizes for a portrait and a screenshot, because the encoder spends its budget where the detail is.

For PNG, quality does nothing — PNG is lossless. Choosing PNG with a max edge of 1600 is a legitimate way to shrink a screenshot without any visible change, and it is often smaller than a low-quality JPG of the same screenshot, because flat colour compresses well losslessly.

Transparent areas are filled white when the output is JPG, since JPG has no alpha channel. Choose PNG or WebP if the transparency matters.

Choosing a target

Web pages: 1600 px on the long edge at 75–80% is a good default — sharp on a laptop, acceptable on a phone, usually under 300 KB.

Email attachments and forms with a 2 MB cap: 1200 px at 70% almost always clears it.

Print: do not compress below about 300 dpi at the printed size, and keep quality at 90 or above. A compressed image that looks fine on screen shows blotches on paper.

Why the result can be bigger than the original

Compressing an already-compressed JPG re-encodes it, and re-encoding always loses a little. If the original was saved at 60% and you compress at 78%, the output can be larger than the input while still looking worse — the detail is already gone, and the second pass cannot restore it.

The same applies when converting a small PNG to JPG at high quality. If the compressed size comes out larger, the honest answer is that the original was already efficient; keep it.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions