I always say to clients something along the lines of: 'If you want it to print at four inches wide, it (the bitmap/photo) needs to be approximately 16 inches across
on screen.
If it's four inches across on screen, it will print approx 1 inch across.
Reason being that 300dpi is
roughly four times 72dpi so this ready-reckoner seems to work well and get through.
I think...
It's always a bugger to explain this concept to people.
