Check the size on a computer
On Windows, right-click the image, open Properties, and read the size on the General tab; the Details tab shows the pixel dimensions alongside it. On a Mac, select the file and press Command plus I, or use Get Info from the File menu.
Both dialogs report the same thing: how many bytes the file occupies on the disk. That number is what an upload form measures when it rejects a file, so compare it directly against the stated limit.
Check the size on a phone
On Android, open the Files by Google app, select the image, and open Details from the menu to see the size in kilobytes or megabytes. Most gallery apps hide this number, which is why the file manager is the quicker route.
On an iPhone or iPad, open the Files app, locate the image, and open its information panel to read the size. If the picture still lives only in your Photos library, save a copy to Files first so the details are available.
Read the number against the limit
Limits are usually written in KB or MB, and the difference matters. Filekind counts 1 KB as 1,000 bytes, so a 2 MB allowance is 2,000 KB, and an image showing 1.8 MB sits comfortably inside it while one showing 2.4 MB does not.
File size and image dimensions are separate values. A photo can measure 600 by 400 pixels and still weigh too much, and a large image can be small if it was compressed well, so check both numbers when a form specifies them.
- KB for small images such as profile photos
- MB for full-size camera pictures
- Pixels for the width and height of the picture
- Compare the size with the limit, not with another file
Check the size after you change the file
The compressor shows the original size and the output size side by side on its result screen, which is the fastest way to confirm a change without leaving the browser. The reported number is measured on the finished file.
Browsers also list downloaded files with their sizes in the downloads page, so you can verify a file straight after saving it. Differences of a few bytes between tools are normal rounding, not a sign that the file changed.
Compress when the file is over the limit
Enter the maximum the destination allows, in KB or MB, and generate. The tool searches for a JPEG at or below that maximum and verifies the final file, because it cannot promise an exactly matching size.
If the first result is still further from the limit than you would like, reduce the pixel dimensions and try again. Smaller images need fewer bytes, and a combined resize and compress pass usually clears even tight requirements.