How to use it
- Choose your photo or drop it into the box.
- Keep the target at 40 KB, or change it to any size you need.
- Check the preview, then download the new file.
Why 40KB?
40KB is a common limit for passport-style photos and scanned signatures on application forms. 40KB is a common cap for small photos. A cropped, plain-background portrait usually fits with little visible loss.
How it works: the tool tries the best JPEG quality that fits under your limit. If quality alone is not enough, it reduces the image dimensions a little at a time until the file fits. Everything happens inside your browser tab, so there is no upload, no account and no watermark.
Tip: if the result looks too soft, crop away empty space first (a smaller picture needs less compression) or raise the target a little.
For the best result at 40KB: (1) crop away empty background, (2) if the form also wants exact pixels, resize first, (3) compress last, because every extra save as JPG adds small artefacts. Keep your original photo in case you need a different size later.
Typical file sizes: a modern phone photo is 2 to 6MB, a screenshot PNG is 300KB to 2MB, and a passport-style crop of 600×600 pixels is usually 60 to 200KB before compressing. Getting to 40KB therefore means reducing the file noticeably, which is why the tool lowers quality and, if needed, dimensions.
Size facts for 40KB: it equals 40,960 bytes (0.039 MB). At ordinary JPEG quality that holds roughly 470×350 to 660×500 pixels of a typical 4:3 photo; detailed pictures sit near the low end, smooth ones near the high end. Compared with a typical 3MB phone photo, a 40KB file is about 99 percent smaller.
Nearby limits: if your form has a different cap, try 35KB (a smaller cap) or 45KB (a larger cap). Other forms may name different caps, so always read the exact limit on the upload page.
More help: read how to compress an image to 30KB, or the passport photo requirements if the upload is for an application.
Questions
How do I compress an image to 40KB?
Choose your photo, keep the target at 40KB and download the result. The tool finds the highest JPEG quality that fits under 40KB and only shrinks the dimensions if it has to.
Is my photo uploaded to a server?
No. Compression runs entirely in your browser, so your image never leaves your device.
Will the quality drop at 40KB?
Some loss is unavoidable when a file gets smaller, but the tool keeps the best quality that still fits the limit. Photos with fine detail lose more than simple images; raise the target if the result looks too soft.
Which formats work?
JPG, PNG and WebP can be used as input. The output is always a JPG, the format that gives the smallest file for photos. Transparent areas of a PNG become white.
Why is my file still bigger than 40KB?
Very large originals (for example 6000 pixels wide) with lots of detail need to be shrunk in dimensions as well. The tool does this automatically. If you still see a larger file, make sure you downloaded the new file and not the original, and try cropping the picture first.
What is the best way to keep a face sharp at 40KB?
Crop so the face fills the frame, use a photo taken in good daylight, and avoid screenshots of photos. A sharp, evenly lit original compresses much better than a dark or blurry one.
Can I compress several images to 40KB?
Yes. Compress them one after another; each file is handled separately in your browser and nothing is uploaded.
Does the picture change shape?
No. The aspect ratio stays the same. If a form needs exact pixels, resize first with the <a href="/resize-image/">resize tool</a> and then compress.
How many pixels fit in 40KB?
Roughly 470×350 to 660×500 pixels for a normal photo, depending on detail. If your form also states exact pixels, resize first and compress last.
How much smaller is 40KB than a phone photo?
Compared with a typical 3MB phone photo, a 40KB file is about 99 percent smaller.