Place your tape measure directly in the middle of the seat post holes and stretch it out until it reaches the end of the bowl – this is your toilet seat length
Again, just like the length, to correctly measure the width you must measure from the toilet bowl’s outside edge on one side to the other outside edge.
If this measurement is 14 inches, you have nothing to worry about. If, however, this measurement is larger or smaller than 14 inches you do in fact have a problem.