How much flooring do you need to do your wide plank flooring job? To be honest, I use cad and put in the layout...then calculate the area automatically, then add 20 percent.
Since you likely don't have access to that, lets give you the simple way. Calculate each room individually. You only need a square foot count, so say your room is 11'-7 x 12'-5. Round up to the nearest number, say 12 x 13, then add 20 percent. Do a sketch of it, so you can show Merv what the job looks like. He will make sure he mills enough material for you to finish.
Do a sketch for each room and allow a 1x6 or 1x8 for thresholds, then add it all up.
I always add 20% to the totals so that I can cut a good few inches off each end before putting the flooring down, and I get to be picky. Some people like the big gnarly irregular knots and cracks and curly grains, and others want only the clean grain. Merv likes the irregular grains, I like clean and only small knots. Everyone has different tastes!
The ends of the boards often are slightly irregular. Planer snipe (the ends of the boards are often planed smaller than in the middle), and sometimes the end of the board is slightly narrower than the middle. Cut off 6-8" and the flooring should go down tight. When you cut off the ends, use the fence on the main part of the board so that it is a perfectly square cut.
Remember, when you install the floor you need to allow 3/4" for expansion and contraction around the outside of the room. Thresholds (separation pieces under the doorways), don't need the space.
The floor above is one of Merv's pine floors with a dark stain on it. It was micro-grooved so that they could prefinish the flooring before putting it in place.