File Calculation Problem

Hi
I have scoured the internet
Is there a formula to calculate file sizes

What I wish to do is find out e.g. how many photos fit on a 1gb card?

A friend has an eye on a point & shoot 16MP Laregest JPEG 4608 x 3456

Can I tell them how many of these files will fit on a 1GB card ?

Thanks for any help

Al