Doyle Log Scale: Estimating Board Feet in a Log
Part of Interior & Finishes
Quick answer
The Doyle log scale estimates the board feet of lumber in a log from its small-end diameter (D, inches) and length (L, feet): BF = ((D − 4)² ÷ 16) × L. It's the most common rule in the eastern US but underestimates small logs.
A log scale predicts how much usable lumber a log will yield before it's sawn. The Doyle rule is the simplest and most widely used in the eastern and southern US, especially for buying standing timber and logs.
The Doyle formula
Board feet = ((Diameter − 4)² ÷ 16) × Length in feet
Diameter is measured inside the bark on the small end of the log. The '− 4' accounts for slab and saw kerf waste.
Doyle scale (board feet per 16 ft log)
| Small-end diameter | Board feet (16 ft log) |
|---|---|
| 12 in | 64 bd ft |
| 16 in | 144 bd ft |
| 20 in | 256 bd ft |
| 24 in | 400 bd ft |
- Doyle underestimates small logs and over-credits large ones, so it favors the buyer on small timber.
- The Scribner and International 1/4-inch rules are alternatives; International is the most accurate.
- Always confirm which scale a buyer or mill uses — the same log scales differently under each.
FAQs
Why does the Doyle scale subtract 4 inches?
The 4-inch deduction approximates the slabs and sawdust lost turning a round log into square boards. It's a rough allowance, which is why Doyle is inaccurate on small-diameter logs.