Calculator Board Feet in a Log
Estimate log volume in board feet using common log rules. Enter the small-end diameter inside bark, log length, quantity, and your preferred rule to compare sawlog values with professional-style output.
How to use a calculator board feet in a log accurately
A board foot is a unit of lumber volume equal to a board that is 1 inch thick, 12 inches wide, and 12 inches long. In raw timber buying and selling, however, standing trees and logs are not measured like neatly edged boards. Instead, foresters, sawyers, and log buyers rely on scaling rules that estimate how much sawn lumber a log can produce. A good calculator board feet in a log helps you turn field measurements into practical numbers for planning, budgeting, timber sales, milling, and rough-cut lumber projects.
The calculator above is designed for common sawlog estimating. It uses the small-end diameter inside bark and the log length to estimate board feet under three traditional log rules: Doyle, Scribner, and International 1/4-inch. Each rule reflects a different assumption about slab loss, taper, saw kerf, and usable lumber recovery. That means the same log can return noticeably different totals depending on the rule selected. This is normal in the forest products industry, and it is one reason every buyer and seller should verify which scaling method is being used before discussing price.
Quick rule of thumb: the larger the log, the smaller the percentage gap tends to be between scaling methods. Smaller logs often show the biggest variation, especially under the Doyle rule, which is known to undervalue small-diameter logs compared with International 1/4-inch.
What measurements you need
To estimate board feet in a log, you only need a few core measurements, but they must be taken carefully:
- Small-end diameter inside bark: this is the diameter at the narrower end of the log after bark is excluded. Diameter inside bark is often abbreviated as DIB.
- Log length: measured in feet. Some buyers measure to the nearest foot, while others may allow trim.
- Number of logs: if you have a truckload, deck, or pile, multiplying by quantity helps estimate total volume quickly.
- Chosen log rule: Doyle, Scribner, or International 1/4-inch.
If your log is highly tapered, crooked, hollow, or damaged, the mathematical estimate may overstate actual yield. Log rules assume more regular geometry than many real-world stems deliver. That is why experienced scalers also apply deductions for sweep, rot, shake, and breakage.
Understanding the three most common log rules
Doyle rule
The Doyle rule is one of the oldest and still appears frequently in private timber transactions in parts of the United States. It is simple and fast, but it tends to penalize small logs because it assumes a large amount of slab waste. For larger logs, Doyle estimates become more competitive. If you are comparing stumpage or roadside prices across different buyers, the scaling rule alone can substantially change the apparent value of your timber.
Scribner rule
The Scribner rule is based on a diagrammatic approach that imagines how boards fit inside the round log. It generally produces values between Doyle and International 1/4-inch. In many markets, Scribner is used for regional consistency, especially where historical mill practices are tied to that scale.
International 1/4-inch rule
The International 1/4-inch rule attempts to account more realistically for saw kerf and taper than older rules. Many forestry professionals consider it the fairest all-around estimate of lumber recovery across a broad range of diameters. When accuracy is especially important, International 1/4-inch is often preferred for comparing logs of different sizes because it tends to be less biased against smaller diameters.
Board foot comparison table for common log sizes
The table below shows representative estimates for a single 16-foot log using the three common rules. These values are calculated using standard formula approximations and demonstrate how the selected rule can affect total board feet.
| Small-end diameter (in.) | Doyle BF | Scribner BF | International 1/4-inch BF |
|---|---|---|---|
| 12 | 64.0 | 71.1 | 61.1 |
| 16 | 144.0 | 154.4 | 168.2 |
| 20 | 256.0 | 260.0 | 323.2 |
| 24 | 400.0 | 397.6 | 506.4 |
| 28 | 576.0 | 567.2 | 717.8 |
These numbers are useful for planning, but they should not replace an official scale in a commercial timber sale. If your local market quotes sawlogs in Doyle and your calculator is set to International 1/4-inch, the same log may look far more valuable on paper than what a buyer will actually pay under local custom.
How the calculator works
When you click the calculate button, the tool applies the chosen log rule formula to the diameter and log length you entered. It then multiplies the result by the number of logs and optionally estimates gross value if you entered a price per board foot. The chart compares all three scales side by side, so even if you price logs using one method, you can immediately see how the others differ.
- Measure the small-end diameter inside bark in inches.
- Measure the merchantable log length in feet.
- Select the scaling rule used by your market, buyer, or mill.
- Enter the number of logs if you want a total instead of a single-log estimate.
- Add an estimated price per board foot to calculate gross value.
- Review the result cards and comparison chart.
Why two logs with the same cubic size may not have the same board feet
Board feet measure potential lumber output, not just geometric volume. Two logs with similar cubic volume can have different board foot estimates if one is longer and slimmer while the other is shorter and wider. Sawing patterns, kerf, edging loss, and taper affect recoverable boards. That is why board foot scaling exists separately from cubic-foot volume calculations.
For practical sawmill work, diameter is especially important. As log diameter increases, mills can saw wider and longer boards while losing a smaller percentage of the total wood to slabs and edging. This is one reason large sawlogs usually command stronger prices per board foot than borderline small sawlogs of the same species and grade.
Comparison table: estimated gross value at $0.85 per board foot
The next table translates board feet into rough gross value using a hypothetical price of $0.85 per board foot. This does not include hauling, scaling deductions, species premiums, or grade adjustments. It simply illustrates how the chosen rule can change pricing.
| Log size | Doyle value | Scribner value | International 1/4-inch value |
|---|---|---|---|
| 14 in. x 12 ft | $63.75 | $66.75 | $79.22 |
| 18 in. x 16 ft | $166.60 | $177.48 | $205.72 |
| 22 in. x 16 ft | $306.00 | $315.18 | $378.22 |
| 26 in. x 10 ft | $257.13 | $252.45 | $314.16 |
Field tips for better log scaling
- Measure inside bark when possible. Bark thickness varies by species and moisture condition, and including bark can inflate volume.
- Use the small end. Log rules are usually based on the narrow end because that constrains recoverable lumber.
- Know your trim allowance. Some mills buy 8-foot, 10-foot, 12-foot, and 16-foot lengths plus trim. Others have stricter merchantable standards.
- Separate species and grades. A board foot of high-grade walnut is not valued like a board foot of low-grade pulpwood-quality hardwood.
- Watch for defects. Sweep, crook, butt flare, rot pockets, and metal all reduce real yield.
- Confirm the buyer’s scale. Price quotes are meaningless without the rule attached to them.
Common mistakes people make when estimating board feet
Using diameter outside bark
This is one of the most common errors. If you measure bark-to-bark and enter that number directly, your estimate may be too high. Thick-barked species and old logs can show a meaningful difference between outside-bark and inside-bark diameter.
Confusing cubic feet with board feet
Cubic volume and board foot scale are not interchangeable. Cubic feet measure physical volume. Board feet estimate sawn lumber output. A log can have substantial cubic volume and still scale lower in board feet if it is too small or too defective for efficient lumber production.
Ignoring the local market standard
If local mills buy by Doyle, then a Scribner or International 1/4-inch estimate is still informative, but not directly equal to what your settlement sheet may show. Always ask what the official purchasing rule is.
Assuming the calculator replaces a grader or scaler
The calculator is excellent for planning, bidding, and educational use. It does not replace onsite inspection for grade, species sorting, defect deductions, or contract terms.
When to use each rule
Use Doyle when your mill, buyer, or region traditionally settles sawlogs on that scale. Use Scribner when you need a middle-ground estimate that many western and historical markets recognize. Use International 1/4-inch when you want a more technically balanced estimate across varied diameters or when a forestry consultant recommends it for appraisal work.
Best practice: if you are negotiating a timber sale, run all three scales, then compare your local bid structure. A low price on a high scale can sometimes equal a higher price on a lower scale. The only fair comparison is total expected dollars under the same rule and deductions.
Authority sources for log scaling and timber measurement
If you want to go deeper into log rules, timber cruising, and sawlog measurement, these authoritative resources are useful starting points:
- USDA Forest Service for forestry measurement guidance, timber sale information, and regional scaling references.
- Penn State Extension for educational material on measuring timber and estimating board feet.
- University of Minnesota Extension for wood products, forest management, and practical log scaling information.
Final takeaway
A calculator board feet in a log is most useful when it helps you make apples-to-apples decisions. Accurate diameter measurement, the right log length, and the correct regional scale are what matter most. The best workflow is simple: measure carefully, choose the log rule that matches your market, compare the other rules for context, and then adjust for species, grade, and defect. If you are buying or selling more than a few logs, this small amount of discipline can make a very large difference in value.
Use the calculator whenever you need a fast estimate for sawing plans, portable mill jobs, private timber sales, or educational comparisons. It gives you a practical board foot total, a value estimate, and a visual chart so you can see how Doyle, Scribner, and International 1/4-inch differ before you make a decision.