Most flooring is sold by the square foot. The square footage is the actual measurement of the area to be covered by flooring. A waste factor of at least 5% must be added to the amount of square footage of flooring needed to allow for cutting waste. Example: a 10' x 10' room = 100 sq. ft. 5% of 100 is 5 so you will have to purchase 105 sq. ft. in order to have enough flooring. If the area to be installed is intricate having a lot of cutting and fitting you may want to use a 10 % waste factor.  This 5-10% extra should also allow culling out boards you may wish not to install.