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KBSize

Compress an image to 300 KB

Set to 300 KB already. Choose a photo and it will find the highest quality that still fits under 300 KB, without uploading anything.

Choose an image and it will be compressed here, in this browser. Nothing is uploaded.

Your image is never uploaded. Compression runs in this browser using the canvas API, and there is no server to send it to. This tool is provided free and without warranty — open the result before you submit it anywhere.

What 300 KB actually allows

300 KB is generous enough for a full-width web image or a detailed photograph at moderate dimensions. Most pictures will reach it on quality alone, with no loss of size.

Nothing is uploaded

The compression happens in your browser. The image is never transmitted, never stored, and disappears when you close the tab — which matters, because files with a size limit attached are usually identity documents.

What fits inside 300 KB

A JPEG spends bytes on detail, so the number of pixels 300 KB can hold depends entirely on how busy the picture is. These are the rough budgets, and they are why a signature can stay large while a photograph of the same size limit has to shrink.

Kind of imagePixels it can affordRoughly, at 4:3
Signature or line drawing6,144,000about 2,860 × 2,150
Passport or ID photo2,560,000about 1,850 × 1,390
Scanned document page1,536,000about 1,430 × 1,070
Detailed photograph930,909about 1,110 × 830

Estimates from typical JPEG output at everyday quality. A detailed photograph gets about 930,909 pixels to work with at 300 KB — near enough 1,110 × 830. Anything bigger has to give up either dimensions or detail, and dimensions are almost always the better thing to give up.

Common questions

How do I reduce a photo to 300 KB?

Choose the file on this page. The target is already set to 300 KB, and the tool searches for the best quality that fits, offering to reduce the dimensions if quality alone cannot get there.

Does it work on a phone?

Yes. It runs in the browser on Android and iOS as well as on desktop, and handles HEIC photos from an iPhone.

What image dimensions fit in 300 KB?

Roughly 1,110 by 830 for a detailed photograph, and much larger — around 2,860 by 2,150 — for a signature or other flat image, because a JPEG spends its bytes on detail rather than on area. The tool works out the real numbers for your specific picture instead of guessing.

Why does my file come out at slightly under 300 KB rather than exactly 300 KB?

Because the target is a ceiling, not a goal. The form you are filling in rejects anything over 300 KB, so the tool searches for the highest quality that still lands underneath and stops once it is close, rather than risking an overshoot.

Other size targets