How to compress an image to 100 KB (or 50 KB, 20 KB)

Application forms, job portals and online stores often ask for a photo “under 100 KB”, “between 20 and 50 KB” or “maximum 200 KB”. A phone photo is usually 2–5 MB, so it has to shrink 20 to 100 times. That sounds drastic, but done in the right order it still looks sharp. Here’s how to hit any size in KB.

The quick way: compress to a target size

1. Open the image compressor on Target size. It runs in your browser, so the photo is never uploaded.
2. Drop in your photo: JPG, PNG, WebP or an iPhone HEIC all work.
3. Type the size you need, for example 100 KB, and press the button.
4. The tool encodes the image repeatedly, narrowing in on the highest quality that still fits, and tells you which quality it used. Download the result.

If the result looks soft or blocky, the photo is too big in pixels for that file size. That’s the next step.

Resize first, then compress

File size depends on two things: how many pixels the image has, and how much data each pixel gets. A 12-megapixel photo squeezed into 100 KB gets very little data per pixel and looks blotchy. The same photo resized to 1200 px wide has a tenth of the pixels, so each gets ten times the data, and it looks crisp at 100 KB.

As a rule of thumb for JPEG photos:

Use Resize Image to set the width in pixels (the height follows, so nothing is stretched), then switch to Compress and set the target size. Both happen in the same tool, on the same image.

If a form also states exact dimensions, such as 600 × 600 px, crop to that shape first (Crop has a 1:1 lock), then resize to the exact size.

Pick the right format

• JPG is what almost every form wants for photos. Use it unless told otherwise.
• PNG is lossless, so it can’t be squeezed to an arbitrary size. A scanned signature or document saved as PNG is often too big; save it as JPG instead, or keep it PNG but make it smaller in pixels.
• WebP and AVIF reach a given size at better quality, but many forms reject them. Use them for your own website, not for uploads.

Open the tool on Target size with a PNG and it switches the output to WebP so it can hit the size, and tells you it did. If the form wants JPG, pick JPEG in Convert before compressing.

Photos and signatures for online application forms

Exam, visa, job and government portals often have strict rules, and they’re the most common reason people search for “compress image to 50 KB”. Check the form’s own instructions for all three of:

• File size: commonly 20–50 KB for a photo and 10–20 KB for a signature, but read the actual limits. Some also set a minimum size.
• Dimensions: often given in pixels (for example 200 × 230) or as a ratio.
• Format: nearly always JPG or JPEG.

Then crop to the required shape, resize to the required pixels, and compress to a size a few kilobytes under the maximum. If there’s a minimum size too, raise the quality until you’re above it.

For a signature, scan or photograph it on plain white paper in good light, crop tightly around it, and resize to the stated dimensions before compressing. A clean, high-contrast signature compresses to a few kilobytes easily.

Can you compress without losing quality?

Not to 100 KB from a full-size phone photo: some detail has to go. But “visible” quality is what matters, and two things keep it:

• Fewer pixels, not lower quality. Resizing to the size the image will actually be shown at throws away detail nobody would see anyway.
• A better encoder. MozJPEG, which the tool uses, produces visibly cleaner JPEGs at the same size than most phone and desktop software.

Compressing also removes the photo’s hidden metadata, such as GPS location and camera details, because the image is re-encoded from its pixels. That’s usually welcome when you’re uploading to a website.

Frequently asked questions

How do I reduce a photo’s size to 100 KB?

Resize it to about 1000–1200 px on the long side, then compress it to a target size of 100 KB as a JPG. A target-size compressor finds the highest quality that fits automatically.

How do I compress an image to 20 KB or 50 KB?

The same way, with smaller dimensions: about 300–500 px for 20 KB and 600–800 px for 50 KB. Crop away anything you don’t need first.

How do I compress a photo on my phone?

Open the compressor in your phone’s browser, pick the photo from your library, set the target size and download. It works in Safari and Chrome on iPhone and Android with nothing to install.

Why is my image still too big after compressing?

It probably has too many pixels for the target, or it’s a PNG, which is lossless. Resize it smaller, or save it as JPG.

Is KB the same as kB or KiB?

Forms use them loosely. 100 KB may mean 100,000 or 102,400 bytes, so aim a few kilobytes under the limit to be safe.