Log scaling rules are formulas or tables used to estimate the board foot volume of logs.

1. Measure DBH: Measure the tree's Diameter at Breast Height (4.5 feet from the ground) in inches.
2. Estimate Usable Height: Estimate the height of the main, straight trunk of the tree up to the point where it begins to branch heavily. This is typically measured in 16-foot log sections.
3. Select a Log Rule: Choose the log scaling rule you wish to use.
   • Doyle: Simple to use, but tends to underestimate small logs and overestimate large ones.
   • Scribner: More accurate than Doyle, based on diagrams of how boards can be cut from different diameter logs.
   • International 1/4" Rule: The most accurate and consistent rule, as it's based on a mathematical formula that accounts for taper and a 1/4" saw kerf.
4. Calculate: The calculator applies the selected formula to your inputs to provide an estimated board foot yield.

Example 1: A 24-inch Walnut
DBH 24", usable height 32' (two 16' logs). Under Doyle, `(24 − 4)² × 2 = 800` board feet.
The same tree under International reads higher, which is why the buyer and seller must agree on the rule first.

Example 2: A Small 12-inch Oak
DBH 12", height 16'. Doyle gives `(12 − 4)² × 1 = 64` BF — modest, and often below the threshold where milling a single tree pays for itself.

• Measuring DBH Wrong: Reading diameter at the flared base instead of 4.5 ft up badly overstates volume.
• Counting Non-sawlog Height: Including the branchy or tapered top in "usable height" inflates the estimate.
• Comparing Different Rules: A Doyle figure and an International figure aren't interchangeable; agree on one rule for a deal.
• Assuming Defect-Free Wood: Real trees lose volume to rot, limbs, and sweep that no log rule models.

"I always scale a tree two or three ways before I bid it. Doyle is kind to the buyer on big sawlogs and rough on the seller for small ones, so knowing the spread tells me how much room is really in the deal." — Timber Appraiser

"Usable height is where most estimates go wrong. Be honest about where the first big limb starts — that's the top of your merchantable log, not the tip of the tree."

• Timber Sales: Establish an agreed board foot volume before pricing stumpage.
• Harvest Planning: Decide which trees are worth felling and milling.
• Land Valuation: Estimate the standing-timber asset on a property.
• Sawmill Scheduling: Forecast expected yield from a woodlot.

• Board Foot (BF): A unit of lumber volume equal to 144 cubic inches (12" x 12" x 1").
• DBH (Diameter at Breast Height): The standard measurement of a tree's diameter, taken at 4.5 feet (1.4m) above the ground.
• Log Scaling: The process of measuring and estimating the volume of lumber in a log or standing tree.
• Log Rule: A formula or table used to perform log scaling.
• Merchantable Height: The clear, usable length of trunk from stump to the first heavy limb.