Timber if made into firewood (cords)
Recovery Rate, suggest entering 0.3 for very small logs, 0.75 for very large logs (10" dia logs ~0.45)
Total board feet of rough sawn lumber

It's fairly easy to estimate the amount of corded wood from timber. Typically you get at least 30% more in volume of corded wood as you would have in uncut wood based on the air space between pieces in cut stacked wood. In going from corded firewood to board feet of lumber, before factoring in the recovery rate, I use a 2/3 conversion. Typically from my experience, it would be closer to 70-75% (the mention of 30% or more volume in corded wood means in this comparison, 1/1.3~77%) as opposed to 67% but this ensures greater safety for the buyer as it is the buyer who could moan about getting his/her correct amount of wood. This would be a small concession from the seller in order to get a deal accomplished.

The recovery rate should be straightforward: if the logs are just 6" in diameter, you can imagine how much actual lumber you could get, with much waste. As you go up in size, the recovery rate quickly goes up then levels out. Note the loss also if there is a big taper to the logs. In a 6" log, factoring in the bark and variability in straightness, you might only get out a single 2"x4" and two 1/2"x2" pieces which in area of the ends is just 10 square inches compared to the log having a 6 inch diameter (3" radius) which is roughly 28 square inches (3^2*pi). And then if you have no use for anything less than a 2x4 in size, your waste becomes greater. I estimate that 10" diameter logs would provide a recovery rate of 45%. A 12" log might be 50%, 15" about 55%, 18" about 65% and slowly increasing as the diameter goes up. These are just rough estimates but good enough to fulfill a much needed purpose.