Calculating Board Feet of a Log: Estimating Sawmill Yield

There is a massive difference between measuring milled lumber and calculating board feet of a log. When dealing with raw, standing timber or felled logs, you cannot simply measure length, width, and height. Because logs are cylindrical and taper from one end to the other, calculating the usable board feet requires specialized forestry scales.

How to Calculate Board Feet in a Log?

To estimate log volume, you must measure the small-end diameter of the log (inside the bark) in inches, and the length of the log in feet. You then apply these measurements to one of three common log scales:

• Doyle Rule: The most common rule in the Eastern and Southern US. It tends to underestimate the yield of smaller logs, providing a built-in safety margin for the sawmill buyer.
• Scribner Decimal C Rule: A diagram-based rule that provides a good all-around estimate, commonly used in the Western US.
• International 1/4-Inch Rule: The most mathematically accurate rule. It accounts for a 1/4-inch saw kerf (the wood lost to sawdust) and a standard log taper of 1/2 inch per 4 feet of length.

Remember: Log Rules are Just Estimates

No log scale is perfect. The actual lumber yield of a log can vary drastically depending on internal defects, sweep (the curve of the log), the species of the tree, and the specific cutting methods used by the sawyer.

To quickly compare the yield estimates of the Doyle, Scribner, and International rules, switch to the "Log Volume Estimate" mode in our Board Feet Calculator.