People ask how to compress image to 1MB and then hit a surprise: the file is 1.02 MB on one screen and 0.98 MB on another. Nothing is broken. Two different ways of counting are in use, and the choice affects whether a strict upload passes.

Counting in 1024

Computers work in powers of two. Under this method, 1 KB is 1024 bytes and 1 MB is 1024 KB, which is 1,048,576 bytes. Many file managers, operating systems and photo tools use this. This page uses it too, so when you type 1 and choose MB, the target is 1,048,576 bytes.

Counting in 1000

Storage makers and some websites count in tens. Here 1 KB is 1000 bytes and 1 MB is 1,000,000 bytes. A file at exactly 1,048,576 bytes shows as about 1.05 MB in this method, which is over a 1 MB limit.

Why the gap matters

The gap is roughly five percent at the MB level. For a normal upload with a loose limit, it makes no difference. For a strict limit, it can decide the result. A file that sits right at the edge can pass on one site and fail on another.

What I suggest

Give yourself a margin. If your limit is 1 MB, ask the tool for 0.9 MB. You lose almost nothing in quality and you clear either way of counting. If you would rather work in KB, 950 KB does the same job.

How to do it here

Drop your picture into the tool above. Set the size box to 0.9 and the unit to MB, or to 1 and MB if you prefer to try the exact number first. Press Compress and read the size beside the preview. The tool saves a JPG, tests many quality levels and keeps the best one that fits. If the picture is very large, it reduces the width and height too.

At 1 MB most photos need only light compression, so the result is usually close to the original in look.

To reduce photo size to 1MB, or to reduce image size in MB for a stricter portal, remember the KB to MB conversion above. A 1MB image is 1024 KB in this tool.

Related sizes

If your limit is smaller, see 500 KB. If it is bigger, see 2 MB. Your photo stays inside your browser and is never uploaded.