Board Feet Calculator Log

Estimate log volume in board feet using common log rules including Doyle, Scribner, and International 1/4-inch. Enter the small-end diameter, log length, and quantity to get an instant lumber scale estimate plus a visual chart comparison.

Log Board Foot Calculator

Tip: Most buyers and mills scale logs using a specific rule. For the most realistic estimate, match the log rule used by your local mill, timber buyer, or forest consultant.

Expert Guide to Using a Board Feet Calculator for Logs

A board feet calculator log tool helps landowners, sawyers, foresters, and woodlot managers estimate how much sawn lumber a log may yield. When someone asks, “How many board feet are in this log?” they are usually trying to understand potential lumber recovery, sale value, or milling efficiency. The answer depends on several factors, but the two most important are the log’s small-end diameter and its length. A good calculator then applies a recognized log rule, such as Doyle, Scribner, or International 1/4-inch, to estimate the amount of lumber in board feet.

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. That means one board foot is exactly 144 cubic inches, or 1/12 of a cubic foot. Logs are not sold by cubic geometry alone in many North American timber markets, however. Instead, they are often scaled with rule-based formulas that try to estimate how much usable lumber can be sawn after accounting for slabs, saw kerf, taper, and waste. This is why the same log can produce different board foot estimates under different log rules.

Why board foot estimates matter

Board foot estimates are useful in several real-world situations. If you own standing timber or harvested logs, you can use a calculator to estimate value before negotiating with a buyer. If you run a portable sawmill, the same estimate can help schedule jobs and price custom sawing. If you are buying logs for woodworking, furniture making, or construction, a board feet calculator log tool helps you compare raw material costs with expected yield. It also improves planning by showing whether one large log is more efficient than several small logs of the same combined cubic volume.

• Foresters use board foot estimates during timber cruises and harvest planning.
• Sawmill owners use them to compare incoming log volume and expected output.
• Landowners use them to estimate stumpage or roadside log value.
• Woodworkers use them to judge whether buying a log is better than buying rough-sawn lumber.
• Students and extension learners use them to understand the difference between geometric log volume and lumber scale.

The three most common log scale rules

The calculator above includes three widely recognized log rules. Each rule estimates board feet differently, and none should be treated as a universal “true” answer. Instead, they are market conventions. Your final value depends on the rule used in your region and by your mill.

1. Doyle Rule: Common in parts of the eastern and southern United States. Doyle tends to under-scale small logs and becomes more favorable as diameter increases. Because of this, small-diameter logs often appear less valuable under Doyle than under other rules.
2. Scribner Rule: Based historically on diagrammed board layouts. Scribner often produces estimates that are between Doyle and International 1/4-inch. It is still used in many markets and remains important in practical log buying.
3. International 1/4-Inch Rule: Often considered the most consistent of the three because it attempts to better account for taper and saw kerf. Many forestry professionals view it as more accurate across a wider range of diameters and lengths.

Because these rules differ, it is not unusual for one 16-foot log to show materially different scale values under each method. That does not mean your calculator is wrong. It means the chosen rule matters.

How this board feet calculator log works

This calculator reads your diameter, length, quantity, and selected rule. It then converts units when needed and applies the chosen formula. The result includes the board feet per log and total board feet for all logs entered. It also compares the same log against all three scale rules in a chart so you can quickly see how the selected method changes the estimate.

The formulas used in many field calculators are practical approximations of standard log rules:

• Doyle: ((D – 4)² × L) ÷ 16
• Scribner: ((0.79 × D²) – (2 × D) – 4) × L ÷ 16
• International 1/4-Inch: ((0.905 × D²) – (1.221 × D) – 0.719) × L ÷ 20

In these equations, D is the small-end diameter inside bark in inches and L is the log length in feet. Logs with very small diameters may produce zero or near-zero values under some rules because they are not considered efficient saw logs.

Sample comparison table for a 16-foot log

The table below shows how estimates can vary by rule for the same 16-foot log lengths. These are calculated values and illustrate why selecting the correct local scale rule is essential.

Small-End Diameter	Doyle Board Feet	Scribner Board Feet	International 1/4 Board Feet
12 inches	64	82	98
16 inches	144	170	177
20 inches	256	276	286
24 inches	400	407	423

Notice the pattern: at smaller diameters, Doyle estimates are usually much lower than the others. As diameter increases, the gap narrows. This is one reason buyers and sellers must always confirm the rule being used before discussing price per thousand board feet.

Board feet versus cubic feet

Board feet and cubic feet are related but not interchangeable. A cubic foot is pure geometric volume. A board foot is a lumber measure based on nominal sawn board dimensions. Since one board foot equals 1/12 cubic foot, it may be tempting to convert a round log’s geometric volume directly into board feet by multiplying cubic feet by 12. In practice, that overstates lumber output because round logs contain bark, taper, edging losses, slabs, trim loss, and saw kerf. Log rules exist because a saw log is not turned into perfect rectangular boards without waste.

Measure	Exact Definition	Use Case	Key Limitation
1 Board Foot	144 cubic inches	Lumber tally and rough output planning	Depends on sawing and recovery assumptions
1 Cubic Foot	1,728 cubic inches	Geometric log volume and biomass work	Does not directly estimate sawn lumber yield
1,000 Board Feet	83.33 cubic feet of lumber	Timber sales and mill reporting	Not the same as 83.33 cubic feet of round logs

How to measure a log correctly

The quality of your estimate depends on how well you measure the log. Most log scale systems use the small-end diameter inside bark because that is the limiting end for sawing. If bark thickness is not removed in the measurement, your estimate may be too high. Log length should also be measured accurately, generally to the nearest foot or according to the scaling convention used by the local market.

1. Measure the diameter at the small end of the log.
2. Measure inside bark if possible, not over bark.
3. Take the average if the log is visibly out of round.
4. Measure usable log length, not total crooked or damaged length.
5. Choose the same rule used by the intended buyer or mill.

If your logs have heavy taper, sweep, butt flare, rot, or other defects, the actual sawn output can differ materially from the calculated board feet. A calculator provides an estimate, not a grading inspection.

Common mistakes people make

The most common mistake is using the wrong log rule. A seller may assume International 1/4-inch because it feels more generous, while a local buyer may legally or routinely purchase under Doyle. Another frequent problem is measuring over bark rather than inside bark. Even a difference of one or two inches in diameter can change board foot results significantly, especially on short or marginal logs.

• Using large-end diameter instead of small-end diameter
• Confusing board feet with cubic feet
• Entering metric dimensions without converting them
• Ignoring defects and assuming all scale becomes usable lumber
• Comparing prices between buyers without confirming scale rule

When a board feet calculator is most useful

This tool is especially useful when you need a fast estimate before a site visit, auction, mill run, or custom saw job. If you are evaluating one or two logs for hobby milling, it can show whether a large-diameter log is likely worth transporting. If you are managing a farm woodlot, it can help approximate total merchantable volume from a stack of bucked logs. If you are teaching forestry or wood products courses, it offers a simple way to demonstrate how scaling conventions affect market numbers.

Still, the best calculators are part of a broader decision process. Log grade, species, defects, taper, transportation cost, local demand, and mill recovery all matter. A high board foot estimate does not automatically mean a high selling price. Some species command higher premiums because they produce valuable appearance-grade boards, while others are sold more for pallet stock, ties, or blocking.

Useful forestry references

For deeper technical guidance, consult these authoritative resources:

• U.S. Forest Service for forestry measurement, timber management, and wood products information.
• Penn State Extension for landowner education on timber measurement and marketing.
• University of Minnesota Extension for practical woodlot and forest management resources.

Final takeaway

A board feet calculator log tool is one of the fastest ways to estimate saw-log volume, but the result is only as good as the measurements and scale rule behind it. Always start with the small-end diameter inside bark, use accurate log length, and match the rule used in your local market. Doyle, Scribner, and International 1/4-inch can all be “correct” within their own conventions, yet they may produce different answers for the same log. By understanding those differences, you can negotiate more confidently, plan milling more accurately, and make better timber decisions overall.

If you want the most practical workflow, calculate your logs under all three rules, compare the spread, and then confirm which one your buyer or sawmill uses. That simple habit helps avoid pricing confusion and gives you a much clearer understanding of real-world log volume.