The photo makes it look much wider than it actually is. It is 7", which, according to many on this board, is the approximate width of the actual belt.
I made it 7 inches to make sure it accommodated the width of the pouch-belt on top of it. If the pouch belt is, say, 3"-4" wide then a 5" girth belt would not allow for much on either side in the way of coverage. It would look way too small, in my opinion. so a 7" belt allows for about 1-2 inches of "peak" above and below the pouch belt.
That said, The belts can be made to whatever width one may want.