Board Feet in a Log Calculator
Estimate lumber yield from a single log or a bundle of logs using common North American log rules. Enter the small-end diameter, log length, quantity, and preferred scale rule to calculate board feet instantly and compare Doyle, Scribner, and International 1/4-inch estimates on an interactive chart.
Expert Guide to Using a Board Feet in a Log Calculator
A board feet in a log calculator helps convert raw log dimensions into an estimated lumber yield. For landowners, sawyers, timber buyers, woodlot managers, and hobby woodworkers, this estimate is one of the most useful numbers in forestry and rough lumber planning. Instead of guessing how much usable material a log contains, you can apply a recognized log rule and create a fast estimate expressed in board feet. One board foot equals a volume of wood measuring 12 inches long, 12 inches wide, and 1 inch thick, or 144 cubic inches.
On paper, the calculation sounds straightforward: measure the diameter, measure the log length, and use a rule. In real practice, however, different log rules produce different results. That is why this calculator includes Doyle, Scribner, and International 1/4-inch methods. These rules were developed to estimate sawn lumber recovery from logs, accounting for slabs, saw kerf, and waste in different ways. If you are comparing stumpage prices, evaluating a portable mill project, or estimating inventory from a load of logs, understanding the chosen rule matters almost as much as the raw measurements.
Important: This calculator estimates board feet from the small-end diameter and log length. In professional scaling, logs may be measured inside bark, lengths may be rounded to merchantable standards, and defects may reduce the net scale. Use this tool for planning and comparison, then confirm measurements if a sale or contract depends on exact figures.
What does board feet mean in forestry?
Board feet is a volume-based unit traditionally used for lumber and log scaling. If a log scales at 200 board feet, that does not mean the log physically contains exactly 200 board feet of solid wood volume. It means that under a specific log rule, the estimated amount of lumber expected from sawing that log is about 200 board feet. This distinction is important. A geometric cylinder volume and a scaled board-foot estimate are not the same thing.
Forestry professionals use board-foot scaling because it creates a common language for valuation and planning. Buyers can compare logs of different diameters and lengths. Mill operators can forecast output. Woodland owners can estimate potential revenue before harvesting. Even woodworkers benefit by understanding how a log translates into rough sawn stock.
How this calculator works
This calculator asks for four core inputs:
- Small-end diameter of the log
- Diameter unit in inches or centimeters
- Log length in feet or meters
- Quantity of logs with the same dimensions
Once values are entered, the calculator converts units as needed and computes the estimated board feet under three common scaling rules:
- Doyle Rule – often used in parts of the eastern and central United States
- Scribner Rule – common in many sawlog markets and western applications
- International 1/4-inch Rule – widely regarded as more consistent across a broader range of log sizes
The selected rule becomes the primary answer, while the chart compares all three methods side by side. That is useful because a log might show a lower estimate under Doyle and a higher estimate under International 1/4-inch, especially when the diameter is smaller. This comparison helps prevent misunderstandings during pricing and inventory review.
The three most common log rules explained
Doyle is one of the oldest log rules still in use. It tends to underestimate smaller logs because of the way it assumes slab loss and kerf. As diameter increases, Doyle becomes less conservative relative to other rules. If you are working with larger hardwood logs in regions where Doyle is customary, it remains highly relevant despite its bias on small stems.
Scribner is based on diagrams of boards that can be cut from logs. It usually produces estimates between Doyle and International 1/4-inch, although the relationship changes with diameter and length. It became widely used because it was practical and relatively simple to apply in the field.
International 1/4-inch is often considered the most balanced of the traditional rules because it better models taper and saw kerf across a range of diameters. Many foresters and extension resources prefer it when accuracy and consistency are priorities, especially for analytical work or educational comparisons.
| Log Rule | Typical Use | Behavior on Small Logs | General Interpretation |
|---|---|---|---|
| Doyle | Common in many eastern and central hardwood markets | Often underestimates strongly | Conservative on small diameters, more favorable on large logs |
| Scribner | Common in many historic and regional scaling systems | Moderate underestimation | Middle-ground estimate in many cases |
| International 1/4-inch | Frequently used in education, analysis, and more consistent scaling | Usually more realistic | Often preferred for broad comparison across diameters |
Example comparison with real calculated estimates
To see why the rule matters, compare estimated board feet for common 16-foot logs. The values below use standard formula approximations like those implemented in this calculator. Actual field scale can differ due to defect deductions, inside-bark measurements, trim allowances, and local scaling conventions.
| Small-end Diameter | Doyle BF | Scribner BF | International 1/4-inch BF |
|---|---|---|---|
| 12 inches x 16 feet | 64 | 83 | 97 |
| 16 inches x 16 feet | 144 | 166 | 202 |
| 20 inches x 16 feet | 256 | 274 | 337 |
| 24 inches x 16 feet | 400 | 407 | 507 |
These examples highlight a central lesson in log scaling: the same physical log can have materially different board-foot values depending on the rule used. In smaller logs, Doyle can be much lower than International 1/4-inch. In larger diameters, the gap often narrows but may still affect sale pricing, timber cruising summaries, and milling expectations.
How to measure a log correctly
- Measure the small-end diameter. This is typically the scaling diameter because it represents the limiting size for saw recovery.
- Use inside-bark diameter if required. Some market systems or references specify inside bark rather than outside bark.
- Measure merchantable length. Standard sawlog lengths are often in even-foot increments such as 8, 10, 12, 14, or 16 feet, plus trim where applicable.
- Record defects separately. Sweep, rot, crook, shake, and scars can reduce the net scale significantly.
- Apply the correct regional rule. Always confirm what buyers, mills, or local foresters use before comparing prices.
When should you use each rule?
If you are selling timber into a market where contracts and buyers quote prices in Doyle, use Doyle for your preliminary estimate so you are comparing apples to apples. If you are evaluating the actual sawing potential of logs for milling, educational analysis, or internal planning, International 1/4-inch often gives a more balanced estimate. Scribner can be useful where that is the traditional market standard or when historical inventory records were prepared under Scribner and consistency matters.
Portable sawmill operators often compare all three. Doing so helps answer practical questions such as:
- How much rough lumber might I recover from these logs?
- What does this load look like under the local market rule versus a more neutral rule?
- How sensitive is the log value to diameter changes of just 1 or 2 inches?
- How much yield difference can species quality and defect erase relative to scale estimates?
Factors that affect real lumber yield beyond the calculator
No calculator can fully capture mill reality. The formulas estimate recoverable board feet under idealized assumptions, but actual output can vary because of:
- Taper: Logs get smaller along their length, and this affects board recovery.
- Saw kerf: Every cut removes wood; blade thickness matters.
- Defects: Rot, knots, metal, stain, checks, and shake reduce usable lumber.
- Crook and sweep: Curved logs are harder to break down efficiently.
- Species and grade: High-value species and better grades may command more value per board foot even if gross volume is similar.
- Mill setup: Thin-kerf bandsaw mills and optimized headrig systems can recover more than rough assumptions suggest.
That is why board-foot estimates should be viewed as planning tools, not promises of exact output. For buying and selling, use the local standard. For milling and woodworking, compare scale estimates with actual sawn recovery records over time.
Best practices for timber buyers, sawyers, and landowners
For timber buyers, consistency is crucial. Use the same measuring method, same bark assumption, and same rule on every tract comparison. For landowners, ask buyers what scale rule they use and whether prices are quoted by board foot, ton, or some other unit. For sawyers, keep a record of actual yield by species and diameter class. Over several jobs, you will learn where each rule tends to overstate or understate what your mill really produces.
It is also wise to remember that board-foot volume and log value are not identical. A lower-grade species with a high volume may be worth less than a smaller high-grade veneer-quality log. Scale tells you how much; grade and market tell you how much it is worth.
Useful reference sources
For more technical guidance, measurement references, and forestry education, consult authoritative public resources such as the U.S. Forest Service, the Purdue University Extension, and the New York State Department of Environmental Conservation. These organizations publish practical information on log scaling, timber measurement, and woodland management.
Bottom line
A board feet in a log calculator is one of the simplest ways to estimate potential lumber output from standing timber or cut logs. Its value comes not only from the number it gives you, but from the comparison it enables. The same log can scale very differently under Doyle, Scribner, or International 1/4-inch. By understanding those differences, measuring carefully, and matching the rule to your market or project, you can make better decisions about harvesting, buying, milling, and inventory planning.
If you want the most practical workflow, start with accurate diameter and length measurements, compare all three rule estimates, and then apply local knowledge about defects, species, and mill recovery. That approach turns a simple board-foot estimate into a much stronger real-world planning tool.