Why is everyone talking inches? NHLA uses standard lengths. What I do, per stack- measure each bd width, add your widths, do this for 4 layers, div and get your average- step back and look at your lengths, get an average length. Ok, you know your thickness, cause you sawed the lumber your self or you told the sawyer how thick you wanted the logs cut. Now do the simple math, your av length X your av width from 3 or 4 layers X thickness divided by 12. There you go, easy as 1 2 3!