I often buy off of the local Tree Surgeons Branches of various Woods and I have an agreed rate based on a Price per Cubic Foot.
To make Calculation easy I use the small Chart below to find the exact amount for each size that I am purchasing and therefore avoid any disagreement over Price, well almost.
|Length Ft. >||1||2||3||4||5||6||7||8||9||10|
I simply sort the Branches by Diameter and then measure the total length and from the Chart I can quickly establish the Volume of Timber in Cubic Feet. i.e. I have 5 Logs approximately all 6″ diameter and with a total length of 18ft, from the Chart I get 1.77ft³(6″ by 9ft) x 2 (to get 18ft) therefore I have 3.54ft³ of Timber.
I carry this around with me, I always have one in my Wallet, one in the Car and yet another in the Workshop and House so I am never without my own little Ready Reckoner, plus a similar one converting Price per Cubic Foot into my Buying Price.