Image Compressor

An exam or job form with a hard size cap

Application portals commonly demand a photo under 100KB, or a signature under 20KB. Type the target and see the real size before you commit to it.

Photos too heavy to send

WhatsApp re-compresses whatever you send, and it does it badly. Compressing first means you decide what gets thrown away.

A page that loads slowly

A phone camera writes 4MB to 8MB per shot. The same picture at a sensible quality is usually a tenth of that with nothing visible lost.

Is it free?

Yes, with no watermark and no page limit.

Does it need an account?

No. There is no account system.

Is my file processed on my device?

Yes. The file is read by your browser and never uploaded. There is no server to send it to.

What formats are supported?

JPG, PNG and WebP in. Each file stays in its own format, so a JPG comes back a JPG. One file out, or a ZIP when you compress several.

What are the limits?

No image count limit. Very large images are bounded by the memory your browser will give a canvas. An image that would grow is returned untouched instead. A target smaller than the picture can physically reach is reported, not silently missed.

Does it work on mobile?

Yes, on any modern mobile browser. Large files are limited by the memory the phone gives the browser.

Does it work offline?

Yes, after you have used it once. Your browser keeps what the tool needs, so it then works with no network connection.

I was told to resize my photo to 20KB. Is that this tool?

Yes. Two different jobs both get called resizing, and an instruction given in KB always means this one. Making an image fewer PIXELS is resizing, which /image-resizer does. Making the FILE fewer kilobytes is compression, which is this page: pick 20 KB, 50 KB, 100 KB, 200 KB or 500 KB, or type any number, and the picture is squeezed until it fits. Upload limits and government forms are written in KB, so a form asking for 20KB wants this page. If the form states pixel dimensions as well, resize first and compress second, because changing the pixels changes the file size again.

How do I compress an image to exactly 100kb, or get it under 20kb?

Switch to "To a size", pick the target, and press the button. It cannot be calculated: the same quality setting produces wildly different file sizes on a blue sky and on a crowd scene, so no tool can jump straight to the answer. This one encodes at a quality, measures the real bytes, and narrows in, usually in three or four goes. If quality alone cannot get there it scales the picture down and tells you it did. If even that cannot reach your target it reports the smallest it managed rather than handing back a file that is still too big, which is the failure you only discover when the upload form rejects it.

How small will my image get?

It depends entirely on the picture, which is why nothing here is estimated. Move the quality slider and the tool re-encodes and shows you the real size. A photograph full of detail compresses far less than a flat screenshot.

What happens if compressing makes the file bigger?

You get the original back, untouched, and the page says so. This is common with small PNGs and with images that are already compressed. A tool called compress that quietly hands you a larger file has failed at the one thing it is for.

Does compressing again make it smaller again?

Barely, and it costs quality every time. JPEG throws detail away on each save, so repeatedly compressing the same photo degrades it while the size hardly moves. Compress once, from the best copy you have.

What quality should I choose?

Around 70 is the usual sweet spot for photos on the web: a large saving that most people cannot see. Go higher if the image is going to be printed or edited further, lower if it is a background or a thumbnail. The size updates as you move, so you can judge it rather than guess.

How this one works

• What is DPI, and why changing it does nothing to your imageWe saved one image at 72, 300 and 1200 DPI. All three were the same bytes and not one pixel differed. What DPI is and what to send instead.
• JPG vs JPEG: the same file, and one of them is a 1980s filename limitThe two extensions are one format. We diffed both: byte identical, same type, same header. What the difference actually was, and when it still bites.
• PNG vs JPG: the answer flips depending on the pictureWe weighed the same image both ways. JPG was 5x smaller on a photo, PNG was 1.5x smaller on a graphic. What is in the picture decides.
• Chrome takes a full second to encode one canvas imageExtracting 9 frames from a video took longer than extracting 174. The cause is a 1000ms idle task timeout in Blink, and the fix is a worker.
• Compress image to 100KB for an upload formA phone photo is several megabytes because of its pixel count, and a form wants 100 KB. What compression throws away, and what to do when it will not fit.

• Image ResizerMake images smaller by pixel size, keeping their format and proportions.
• PNG to WebPTurn PNG and JPG images into WebP, which usually lands smaller at the same quality.
• JPG to PNGTurn JPG photos into PNG files that will not lose any more detail.
• Resize Image to KBFit a photo or signature inside the pixels a form asks for and under its KB limit.
• Grayscale imageConvert a colour image to black and white.
• Image ConverterConvert images to JPG, PNG, WebP, GIF or BMP, in a batch, with the output your choice.