Almost every week there seems to be a post in the Alamy Forum in which a new contributor is struggling to understand the Alamy submission requirements for file size.

The website info is quite clear...

Q. What file size do I need to upload?
A. We need a JPEG file size of over 17MB when uncompressed (this is likely to have a compressed JPEG size of 3-5MB). Opening a JPEG in an image program such as Adobe Photoshop will show you the uncompressed (open) file size.

This still doesn't seem to answer the questions which are posed in the forum, so the best solution is to always use this small standalone App from Braeside Communication Services. Download here... AlamySizeCheck
 

Image2

As you can see, it shows the compressed size and also the uncompressed size. It will show a warning if the file size falls below the threshold.
The two files shown in the image above are fine to upload to Alamy.

A donation to David Anderson would be nice.