How do I compress an image to under 500 KB?

Use a target-size compressor: set 500 KB as the target and it finds the highest quality that fits, reducing the dimensions only if needed. Resizing large phone photos to around 2000 px first helps a lot.

How do I get an image under 100 KB?

Reduce the pixel dimensions first, then compress. A 1000 × 1000 image at moderate quality fits far more easily than a 4000-pixel photo compressed hard.

Why does my image look blocky after compression?

The quality was pushed too low to hit the size. Reduce the image dimensions instead and use a higher quality.

Why is the compressed file bigger than the original?

The original was already heavily compressed. Keep the original in that case.

How to Compress an Image to a Target Size (Under 500 KB, 200 KB or 100 KB)

"Image must be under 500 KB" is one of the most common upload errors. The quick fix — dragging a quality slider down until it fits — usually throws away more quality than it needs to. Here is a better way.

Why the file is too big

File size comes from two things: how many pixels the image has, and how heavily each is compressed. A phone photo of 4000 × 3000 pixels has 12 million pixels. A product listing rarely shows more than 2000 pixels across. Most of the file is detail no one will ever see.

So the first lever is dimensions, and the second is quality. Cutting the longest side from 4000 to 2000 pixels removes three-quarters of the pixels before compression even starts.

How target-size compression works

Hitting an exact limit by hand is trial and error. A target-size compressor does the search for you:

It encodes the image at a middle quality and checks the size.
Too big? It tries a lower quality. Comfortably under? A higher one.
After a few rounds it keeps the highest quality that still fits.
If even low quality is too big, it shrinks the dimensions a step and repeats.

That last step matters: a large photo forced under 100 KB by quality alone looks blocky, while the same photo at a smaller size and a reasonable quality looks clean.

Step by step

Open the image compressor and add your images.
Choose JPG if you are not sure where the image is going — it is accepted almost everywhere.
Select Target file size and enter the limit in KB, a little under the real limit to leave margin.
For large phone photos, tick limit the longest side and set 2000 px.
Compress, check the result, and download.

What sizes are realistic?

It depends on the image — a plain product on white compresses far better than a busy, detailed scene. As a rough guide, a 1000 × 1000 product photo on a plain background usually fits comfortably within a few hundred KB at good quality. Very small targets on very detailed images will show artefacts whatever the tool does; if that happens, use a smaller pixel size rather than a lower quality.

When not to compress

If the compressed file comes out larger than the original, the original was already well compressed. Keep it. Re-encoding an already-compressed JPG cannot make it both smaller and better.

Try it: Compress an image to a target size — free, no signup, runs in your browser.