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 board feet calculator for logs work?
Enter the small-end diameter inside the bark (the limiting dimension) and the log length in feet. The Doyle log rule 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.
That is also why an ordinary log bd ft calculator built for squared boards cannot be used here unchanged — a round stick has no thickness and no width to enter, only a diameter, so the loss to slab and edging has to be part of the formula rather than an adjustment you remember afterwards.
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 board feet are only a yield estimate, not the surfaced boards 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.
That per-section repetition is the whole trick — a board feet calculator for a tree is not a different formula, it is this one run section by section, which is also what a standing timber calculator does across a cruise plot. A log board foot calculator stops at the first log because the scale is already on the ticket.
How to figure board feet in a log by hand
Figuring board feet in a log at the landing rarely involves a calculator, and a skidder operator does not care which rule you prefer. The Doyle log rule is the only one of the three you can do in your head, because it is a single formula; Scribner and International ¼″ are published as diameter-by-length tables, so a hand figure there is really a lookup. Four steps, and you are done:
- Measure the small-end diameter inside the bark in whole inches. Bark is not lumber; if you cannot get inside it, take the outside reading and treat it as the ceiling, not the number.
- Subtract 4 — Doyle’s standing allowance for slab and edging — then divide by 4.
- Square the result. That is your board feet per foot of log length.
- Multiply by the length in feet.
| Diameter | (D − 4) ÷ 4 | Squared = BF per foot | 8′ log | 16′ log |
|---|---|---|---|---|
| 12″ | 2.00 | 4.00 | 32 BF | 64 BF |
| 14″ | 2.50 | 6.25 | 50 BF | 100 BF |
| 16″ | 3.00 | 9.00 | 72 BF | 144 BF |
| 18″ | 3.50 | 12.25 | 98 BF | 196 BF |
| 20″ | 4.00 | 16.00 | 128 BF | 256 BF |
| 24″ | 5.00 | 25.00 | 200 BF | 400 BF |
Read the last two columns sideways. A 24″ log is only 20% thicker than a 20″, yet it scales 56% higher (200 BF against 128 BF on the same 8′ stick) — because the formula squares (D − 4), and 20 ÷ 16 squared is 1.56. Length is the only part that stays linear: doubling an 8′ log to 16′ doubles its scale, nothing more. That asymmetry is why a load of thin logs is so easy to under-price, and why a bd ft calculator for sawn boards cannot be swapped in here — a board is measured on three separate dimensions, not one squared diameter.
Loads are usually priced in MBF (thousand board feet), so divide the chart total by 1,000: the 12-log load above at 967.92 BF International ¼″ is 0.97 MBF, and a $600-per-MBF gate rate is $0.60 per board foot. A log scale calculator and a sawmill calculator are the same arithmetic — the mill is just applying its own recovery assumption on top of the scale.
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 the Doyle log rule give a lower board foot count?
The Doyle log rule 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.
Can I use a board foot calculator on a log instead of a log rule?
Not meaningfully. A board foot calculator measures lumber that already exists — thickness × width × length ÷ 12 — while a log rule predicts lumber that a saw has yet to release, so it has to build in slab, edging and kerf loss. Feed a round log into an ordinary bd ft calculator and you will price the cylinder, not the boards; the cylinder is the number that is too big.
Is a log board foot chart the same thing as a log rule?
Yes, in printed form. A log board foot chart is one of these rules laid out as diameter × length so a scaler can read the answer off paper — the Doyle chart above is exactly ((D − 4) ÷ 4)² × L, tabulated. Scribner and International ¼″ are published as tables first and formulas second, which is why you will see a paper chart at the mill gate and a calculator on the web.
How do I measure board feet in a log with nothing but a tape?
Wrap the tape around the small end to get the circumference, divide by 3.14 and you have the diameter over the bark; knock off roughly an inch for bark to get the inside-bark figure. Measure the length in feet, then read the Doyle chart: 16″ small end → 9 BF per foot → 72 BF on an 8′ log. That is the whole field method — every figure board feet in a log shortcut is this, rounded.