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 — scale a whole truckload at once or size a standing tree from its DBH, 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.
What does a mixed truckload scale to?
Single-log examples hide the part that actually moves money: a load is a mix, and the rules do not disagree by a fixed percentage across that mix. Here is a real-ish 12-log load of 8-foot sawlogs — six 12-inch, four 16-inch, two 20-inch — scaled three ways from the published formulas.
| Log size | Count | Doyle, per log | Scribner, per log | Intl ¼″, per log | Doyle vs Intl |
|---|---|---|---|---|---|
| 12″ × 8′ | 6 | 32 BF | 42.88 BF | 48.66 BF | −34.2% |
| 16″ × 8′ | 4 | 72 BF | 83.12 BF | 93.14 BF | −22.7% |
| 20″ × 8′ | 2 | 128 BF | 136 BF | 151.70 BF | −15.6% |
| Load total | 12 | 736 BF | 861.76 BF | 967.92 BF | −24.0% |
Read the last column from the bottom up. Doyle is 24% light on the load as a whole — but that average is built from a 34% haircut on your small logs and only 16% on your big ones. The rule does not under-scale logs; it under-scales thin logs. If a buyer wants Doyle on a load heavy in 12s and 14s and is happy to talk International on the 20s, now you know what he is actually doing.
Priced at a $3.50 gate rate the load is worth $2,576 under Doyle against $3,388 under International ¼″ — an $812 spread on logs already cut, skidded and hauled. Tally the same arithmetic on any project's finished boards with the lumber cost calculator once the log rule is settled.
Hauling is the number that moves before anyone argues about scale. The same 12 logs weigh markedly more green than they will after air-drying, so the tonnage on the trailer and the freight bill are set by moisture as much as by size — the board foot weight calculator works that out from the tally you settled on.
How much wood is actually in the log?
Every log rule reports less than the log physically contains, because a saw cannot turn a cylinder into square boards. That gap is the only honest way to judge whether a scale figure is generous or stingy, so I put the standing volume next to each rule. Treating each log as a cylinder on its small-end diameter, this load holds about 1,407 board feet of wood:
| Basis | Board feet | Share of the wood in the log |
|---|---|---|
| Standing volume (small-end cylinders) | 1,407.43 BF | 100% |
| Doyle scale | 736 BF | 52.3% |
| Scribner scale | 861.76 BF | 61.2% |
| International ¼″ | 967.92 BF | 68.8% |
International ¼″ is the closest of the three to what a competent sawyer recovers, which is why it is the rule most state forest programs and extension services appraise with. The gap between 52% and 69% is not a rounding quirk — it is the same cylinder, divided differently.
How many board feet are in a standing tree?
A tree is just a log that is still attached to something, so the same three rules apply — you only have to do two extra steps first. Measure DBH (diameter at breast height, 4.5′ above the ground) on the outside of the bark, then scale on the inside-bark diameter, because bark is not lumber. Then divide the clear stem into the lengths a mill will actually take — 8′ is the usual sawlog — and scale each section on its own small-end diameter, because the trunk gets thinner as it goes up.
Take a black walnut with 16″ DBH and 16′ of clear, merchantable stem. Strip roughly an inch of bark and taper between sections and you are scaling a 15″ first log and a 14″ second log — that taper allowance is my field assumption, not a species constant, and a cruiser with a scaling stick will measure it rather than guess it:
| 8′ log section | Small-end diameter | Doyle | Scribner | International ¼″ |
|---|---|---|---|---|
| Butt log (first 8′) | 15″ | 60.50 BF | 71.88 BF | 80.70 BF |
| Second log | 14″ | 50.00 BF | 61.42 BF | 69.14 BF |
| Tree total | — | 110.50 BF | 133.30 BF | 149.84 BF |
| Share of the wood in the stem | 220.44 BF | 50.1% | 60.5% | 68.0% |
At the $3.50 gate rate used in the truckload example above, that single tree is worth $386.75 to a Doyle buyer and $524.44 under International ¼″ — a $137.69 spread on a tree that has not been felled yet. Two things this section deliberately does not do: it does not scale the limbs, stump or a rotten core, all of which are real wood but not merchantable lumber, and it does not apply a grade. Timber cruising adds grade tables on top of the same diameter-and-length arithmetic, so a cruiser's number will sit below a raw scale of the stem.
Frequently asked questions
Which log rule should I use?
Doyle is common in the eastern US but under-scales small logs under about 28 inches. Scribner is widely used on the West Coast and by the Forest Service. International ¼″ is the most accurate of the three and is the one used for research and many state timber sales. Ask which rule is on the ticket before you argue about the number.
Why does Doyle give a lower board foot count?
Doyle subtracts four inches of diameter for slab and edging before squaring the remainder, so the penalty falls hardest where the log is already thin. On the 12-inch logs above it reads 34% below International ¼″; on the 20-inch logs only 16% below. The rule did not change — the diameter did.
How many board feet are in a standing tree?
Scale the tree log by log. Take DBH at 4.5 feet, subtract bark to get the inside-bark small-end diameter, divide the merchantable stem into 8-foot sections, and scale each section on its own small-end diameter. A 16-inch DBH walnut with 16 feet of clear stem scales to about 110 board feet in Doyle, 133 in Scribner, and 150 in International ¼″.
Is log scale the same as finished board feet?
No. Log scale estimates the lumber that can be sawn from a log. It says nothing about what survives drying and surfacing, where the tally basis changes again — see gross vs net tally. Actual recovery depends on the sawyer, the taper and the defects you cannot see from the small end.