For logs & standing timber
Log Board Foot Calculator
Estimate a log's board-foot yield with the three standard rules — Doyle, Scribner, and International ¼-inch — then use the main board foot calculator for finished boards.
Which log rule should you use?
A log rule is a formula that estimates the board feet of lumber a log can produce. The three rules give different numbers for the same log because each makes different assumptions about saw kerf, slab waste, and taper. A log rule predicts yield from a round log; once that log is sawn into boards you switch to the plain volume formula in how to calculate board feet.
In twenty years of buying I've learned to ask one question before anything else: which rule is on the ticket? Doyle, Scribner, and International ¼-inch can disagree by a third on the same small log, so the rule choice is the negotiation.
| Rule | Best for | Tendency |
|---|---|---|
| Doyle | Eastern US trade | Under-scales logs under ~28″ diameter |
| Scribner | Western US, USFS | Moderate; ignores some taper |
| International ¼″ | Research, state sales | Most accurate; tracks real recovery |
How does the calculator scale a log?
Enter the small-end diameter inside the bark (the limiting dimension) and the log length in feet. The Doyle formula is ((D − 4) ÷ 4)² × L; Scribner and International ¼-inch use their own published formulas, with International computed in 4-foot sections to account for taper.
If a buyer quotes you in Doyle scale on small logs, you may receive far more usable lumber than the scale suggests — good for the buyer, not the seller. Knowing which rule is in play is the whole game when selling timber.
What does a 12-inch log yield under each rule?
Here's the example I use to show why the rule matters. Take a small sawlog — 12-inch small-end diameter, 16 feet long — and scale it three ways. Doyle works straight from the formula: ((12 − 4) ÷ 4)² × 16 = 2² × 16 = 64 board feet. Scribner reads about 80 board feet, and the International ¼-inch rule lands near 95 board feet.
| Log rule | Estimated yield | vs International ¼″ |
|---|---|---|
| Doyle | 64 BF | −33% |
| Scribner | ≈ 80 BF | −16% |
| International ¼″ | ≈ 95 BF | baseline |
That 31-board-foot gap between Doyle and International is real money on a single log, and it widens as the log gets smaller. If you're selling, Doyle scale on small timber quietly hands the buyer free lumber. Once the sawyer breaks the log down, tally the finished boards by actual size in the hardwood board foot calculator — log scale is only a yield estimate, not the surfaced board feet you'll sell.
If the term itself is fuzzy, I'd start with the definition in what is a board foot: a log rule still reports its answer in those same 144-cubic-inch units, even though it's predicting volume that doesn't exist yet.