Introduction
A log scale formula is only as honest as the two numbers fed into it. Diameter read at the wrong end, bark included, length taken on the long side – each of these small field errors compounds through the squaring in the formulas into a meaningfully wrong board-foot total. Accurate estimating is a field craft: the right tools, the right measuring points, a consistent routine, and a tally sheet that anyone can audit.
The Log Board Feet Calculator turns diameter (inches) and length (feet) into Doyle, Scribner, and International 1/4-inch board footage. This guide covers how to produce inputs worth calculating with: the tools, the measuring conventions for diameter and length, how to handle oval and tapered logs, and how to tally a whole log deck without losing track. For what the formulas do with your numbers, see the formula-explained guide.
Tools for Scaling Logs
The right tools make the work faster and more defensible:
- Tape measure (25 ft / 7.5 m): the basic tool for diameter (via circumference) and length.
- Diameter tape: reads diameter directly from circumference – the traditional scaler’s tool.
- Log calipers: span the log end for a direct reading; excellent for small ends and oval logs.
- Log scale stick: reads board feet directly for a given length at the small end. Fast for rough tallying; the calculator is more precise.
- Tally sheet and marker: record log number, species, diameter, and length for every log. A tally nobody wrote down is a tally nobody can defend.
- Metal detector (handheld): essential for yard trees – see the material guide.
- Hammer: sounding for rot – a clear ring means sound wood, a dull thud means decay.
Measuring Diameter: The Exact Procedure
Diameter is the high-leverage measurement – the formulas square it, so a 1-inch error on a 14-inch log moves the Doyle result by about 15 percent. Follow this routine:
- Go to the small end. Every scale is defined on the small-end diameter. If the small end is buried, expose it before measuring.
- Measure inside the bark. Press the tape through the bark to the wood, or measure bark thickness on the cut face and subtract twice the bark thickness from an outside reading. Bark thickness of 0.25 to 1 inch per side (0.6 to 2.5 cm) is typical.
- Take two readings on oval logs. Measure the widest and narrowest diameters and average them. A 17 by 15-inch (43 by 38 cm) log enters the calculator as 16 inches.
- Measure at the cut face, not back along the log. The small-end face is the defined point; measuring back where the log swells adds phantom diameter.
- Round to the nearest whole inch (nearest centimeter in metric, then convert). Finer precision is false accuracy against the formulas’ approximations.
Measuring Length: The Exact Procedure
- Measure the shortest side. Log ends are cut at angles; the shortest side is the usable length the mill can saw.
- Enter the nominal footage. A log cut 12 ft 4 in (3.76 m) for trim allowance is a 12-foot log for scaling purposes – enter 12, not 12.33.
- Note odd lengths separately. A 9-foot or 13-foot log still scales by the formula, but odd lengths limit what the mill can cut and may price differently. Flag them on the tally.
- Check for excessive trim. More than 6 inches (15 cm) of trim on a short log is wood you are giving away – re-cut or account for it.
Tallying a Log Deck
For more than a couple of logs, work systematically. Number each log (crayon or lumber marker on the end), and record species, diameter, and length in a table:
| Log # | Species | Diameter (in) | Length (ft) | Doyle (BF) | Notes |
|---|---|---|---|---|---|
| 1 | Red oak | 16 | 12 | 108 | Straight, sound |
| 2 | Red oak | 14 | 10 | 63 | Slight sweep |
| 3 | Walnut | 18 | 8 | 98 | Sort separately – premium |
| 4 | Red oak | 12 | 12 | 48 | Small – check scale with buyer |
Verify the arithmetic: log 2 Doyle = (14 – 4) squared x 10 / 16 = 100 x 0.625 = 62.5, rounded to 63 BF. Log 3 = (18 – 4) squared x 8 / 16 = 196 x 0.5 = 98 BF. Log 4 = (12 – 4) squared x 12 / 16 = 64 x 0.75 = 48 BF. The four-log tally totals 317 BF Doyle – about 0.748 cubic meters.
Sort premium species and large diameters onto separate tally lines. A mixed deck priced at one rate earns the rate of its cheapest member – the sorting hour pays for itself, as noted in the pro tips guide.
Estimating a Truckload
A standard log truck carries roughly 4,000 to 5,000 BF (Doyle) – about 9.4 to 11.8 cubic meters of board-foot equivalent – though weight limits usually cap the load before volume does. Green hardwood can hit legal road limits (typically 80,000 lbs / 36,300 kg gross in the US) well before the trailer looks full.
To estimate a truckload: scale a representative sample, compute the average BF per log, and multiply by the log count. If 25 logs average 130 BF, the load is about 3,250 BF – roughly $1,950 at $600 per MBF for standard hardwood, before haul costs. Pricing is covered in the cost guide.
Metric Workflow
Working entirely in metric? Measure diameter in centimeters and length in meters, then convert at entry: cm / 2.54 = inches, m / 0.3048 = feet. A 41 cm by 3.7 m log becomes 16.1 inches by 12.1 feet – enter 16 and 12. Record both the metric readings and the converted inputs on the tally sheet for auditability. Convert results back with 1 BF = 0.0023597 cubic meters. As an independent check, the Smalian formula (log volume = average end cross-section x length) gives about 0.49 cubic meters gross for this log against roughly 0.26 cubic meters of Doyle board feet – a plausible 53 percent recovery confirming the inputs are sane.
Quality Checks Before You Trust the Tally
- Re-measure outliers. Any log reading far above or below its neighbors gets measured twice.
- Cross-check with a second rule. Spot-check a few logs with International against Doyle – the expected spread (large gap on small logs, small gap on big logs) confirms the inputs are consistent.
- Walk the tally with the other party before money moves. A disputed tally after payment is a much harder problem.
- Photograph the deck. Dated photos of numbered log ends are cheap evidence if a tally is questioned later.
The errors these checks catch are catalogued in the common mistakes guide.
Related Guides
- Complete Guide – log board feet basics, the three scales, and a full worked example.
- Formula Explained – the Doyle, Scribner, and International 1/4-inch math step by step.
- Material Guide – species, quality, and defect deductions that affect value.
- Pro Tips – practical advice for buying, scaling, and milling logs.
- Cost Guide – typical log prices per MBF and what moves them up or down.
- Checklist – everything to verify before you buy, scale, or mill a log.
Frequently Asked Questions
What tools do I need to scale logs?
A tape measure, a tally sheet, and a marker will do. A diameter tape and log calipers speed things up; a metal detector and hammer help evaluate yard-tree logs for metal and rot.
How precise should my diameter measurement be?
Nearest whole inch (nearest centimeter, then convert). The formulas approximate real sawing – finer precision is false accuracy.
How do I estimate a whole truckload quickly?
Scale a representative sample, compute average BF per log, and multiply by the log count. Weight limits usually cap the load before volume does.
Should I measure every log or sample?
Measure every log for small lots and any sale. Sampling suits only large, uniform decks – and even then, verify the sample against the buyer’s tally.
What is a Biltmore stick?
A calibrated stick that reads board feet directly for a given log length at the log’s small end. Fast for rough field tallying; the calculator is more precise and documents the inputs.
How do I handle metric measurements in the field?
Measure in cm and m, convert to inches and feet before entering (divide by 2.54 and 0.3048), and record both sets of numbers on the tally sheet for auditability.
Get Your Number
Accurate estimating is a routine: small end, inside bark, two readings on oval logs, shortest side for length, nominal footage, every log numbered and recorded. Run the measurements through the Log Board Feet Calculator, reconcile your tally with the other party’s before money moves, and keep the sheet – a documented tally is the foundation every fair log deal stands on.
Disclaimer: Calculator results are planning estimates based on the dimensions you enter. Actual lumber recovery varies with species, log quality, defects, sawing method, and kerf. For commercial timber sales, consider a professional scaler or forester, and verify volumes independently before committing.
