How To Calculate Board Feet Of A Tree

Use this premium calculator to estimate board feet from a log or a merchantable section of a tree. Enter the small-end diameter, usable log length, quantity, kerf or waste allowance, and your preferred rule. The calculator instantly returns total board footage and a visual comparison chart.

Tip: For standing trees, estimate merchantable log sections first. Measure the small-end diameter of each section and calculate each log separately for the most realistic total.

Expert Guide: How to Calculate Board Feet of a Tree

Knowing how to calculate board feet of a tree is one of the most practical skills in forestry, sawmilling, logging, and hardwood buying. 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. Because rough logs are round and lumber is sold in flat, sawn dimensions, calculating board feet from a tree requires an estimating method rather than a perfect one-to-one conversion. That is why foresters, timber buyers, and small mill operators use standard log rules and field measurements to estimate how much usable lumber a log or standing tree can produce.

At the most basic level, you need two things: diameter and length. Diameter is usually measured in inches, and log length is measured in feet. If you are estimating an individual log, you typically use the small-end diameter inside bark because it better reflects the limiting sawing dimension. If you are estimating a standing tree, you often start with diameter at breast height, then estimate how many merchantable logs the trunk contains, and then apply a board foot rule log by log.

What a board foot means in practical terms

A board foot is a measure of volume, not a count of boards. For example, all of the following equal 1 board foot:

• 1 inch thick x 12 inches wide x 12 inches long
• 2 inches thick x 6 inches wide x 12 inches long
• 1 inch thick x 6 inches wide x 24 inches long

This matters because a round log can contain many possible board combinations. The estimate depends on defects, taper, kerf loss, slab loss, crook, sweep, and species quality. The board foot rules discussed below attempt to standardize those real-world losses.

The simplest board foot formula

If you want a fast approximation, use this simple cylindrical estimator:

Board Feet = (Diameter in inches x Diameter in inches x Length in feet) / 16

This formula treats the log more generously than some traditional log rules because it does not fully account for sawing waste and taper. Still, it is useful for rough planning, farm use, and quick comparisons between logs of similar shape. For example, a log with an 18-inch small-end diameter and a 16-foot length would be estimated as:

1. Square the diameter: 18 x 18 = 324
2. Multiply by length: 324 x 16 = 5,184
3. Divide by 16: 5,184 / 16 = 324 board feet

That gives a gross estimate before waste allowance. If you apply a 10% waste deduction for edging, defects, and handling loss, net board feet would be 324 x 0.90 = 291.6 board feet.

Common log rules used in the United States

In professional timber work, the three most discussed systems are the Doyle rule, Scribner rule, and International 1/4-inch rule. Each rule estimates recoverable board footage differently. The reason the numbers differ is simple: each rule assumes different amounts of slab loss, saw kerf, and taper. That means there is no single universal answer for every species, mill, and region.

• Doyle rule: often used in many hardwood markets and known for underestimating small logs while becoming more favorable on large logs.
• Scribner rule: based on a diagrammed sawing pattern and commonly used in western and mixed regional markets.
• International 1/4-inch rule: often considered more consistent because it accounts for taper and kerf more explicitly.

This calculator includes a simple estimator, the Doyle rule, and the Scribner rule because they are widely recognized and useful for quick field work. If you are selling logs commercially, always confirm which rule the buyer or mill uses before pricing timber.

Rule or Method	Typical Formula Used for Estimation	Best Use	Important Limitation
Simple estimator	D² x L / 16	Quick planning and farm estimates	Can overstate yield because waste is not built in
Doyle	((D – 4)² x L) / 16	Common hardwood trade estimate	Often undervalues smaller logs
Scribner	((D² – 4D – 4) x L) / 16	Field and trade comparison	Still an estimate, not actual mill tally

How to measure a tree for board feet

To calculate board feet of a tree accurately, divide the process into a few clear steps.

1. Measure diameter. For logs, use the small-end diameter inside bark if possible. For standing trees, start with diameter at breast height, then estimate the merchantable upper stem diameter and likely log sections.
2. Measure merchantable length. Determine how many sawlog sections the trunk contains. Length is usually measured in standard sawlog increments such as 8, 10, 12, 14, or 16 feet, plus trim allowance if needed.
3. Select a rule. Use the same rule your market or mill uses. If you are simply planning lumber output, compare at least two methods.
4. Calculate each section. Logs from the butt, middle, and top of the tree can have different diameters and quality. Estimate each log separately, then add the totals.
5. Apply waste or defect deductions. Rot, sweep, knots, cracks, and taper reduce recoverable lumber.

Many people make the mistake of measuring only DBH and total tree height, then trying to convert directly to board feet. That can lead to inflated expectations. A better method is to estimate only the merchantable stem and then break that stem into realistic sawlog sections.

Real-world comparison of log rule outputs

The table below compares common outputs for straight 16-foot logs using the same measured small-end diameter. These figures show how much the rule selected can change the estimated lumber tally. The formulas are standard field approximations and are rounded to the nearest whole board foot for readability.

Small-End Diameter	Length	Simple Estimator	Doyle	Scribner
12 in	16 ft	144 BF	64 BF	92 BF
16 in	16 ft	256 BF	144 BF	188 BF
20 in	16 ft	400 BF	256 BF	316 BF
24 in	16 ft	576 BF	400 BF	476 BF

Notice the spread in values. A 16-inch by 16-foot log can estimate at 256 board feet using the simple formula, 144 board feet using Doyle, and 188 board feet using Scribner. This is why a seller and buyer must agree on the rule in advance. If you ignore that detail, pricing confusion is almost guaranteed.

Typical factors that change actual recovery

No calculator can fully replace scaling, grading, and sawing experience. Actual board yield depends on factors such as:

• Taper: Trees get narrower toward the top, reducing recoverable width in upper logs.
• Defects: Rot pockets, ring shake, seams, scars, and insect damage lower output.
• Sweep and crook: Curvature reduces usable straight lumber.
• Saw kerf: Wider blades remove more wood as sawdust.
• Mill strategy: Grade sawing, live sawing, quarter sawing, and custom sawing all affect recovery.
• Species and quality: Straight, clear hardwood stems often recover more marketable value even if raw volume is similar.

A practical rule is to calculate gross board feet first, then apply a waste deduction of 5% to 20% depending on the tree, the log section, and your mill expectations. Cleaner butt logs often need a lower deduction than upper, knotty, or mixed logs.

How to estimate board feet from a standing tree

If the tree is still standing, use a field sequence rather than a single shortcut. First, measure DBH at 4.5 feet above the ground. Second, determine merchantable height, usually the number of sawlogs to a top diameter limit. Third, estimate the small-end diameter of each merchantable log section. This can be done with experience, a cruising stick, a diameter tape on felled sections, or formal timber cruising tools. Once you have those individual log dimensions, calculate each log’s board feet and sum them.

For example, suppose a tree produces two merchantable 16-foot logs. If the first log scales 20 inches at the small end and the second scales 16 inches, a simple estimate would be:

• Log 1: 20² x 16 / 16 = 400 BF
• Log 2: 16² x 16 / 16 = 256 BF
• Total gross = 656 BF

If you apply a 12% deduction for defects and waste, net board feet would be about 577 BF. This staged approach is much more realistic than trying to convert the whole trunk from one average diameter.

When to use board feet versus cubic volume

Board feet are ideal when the end goal is lumber. Cubic feet or cubic meters are more appropriate when measuring total wood volume, biomass, or pulpwood. In many timber markets, pulpwood is sold by weight or by cord, while sawtimber is sold by board foot. If you are evaluating a mixed stand, separate trees by end use before estimating value.

Best practices for better field estimates

1. Measure the small end of each log, not the large end.
2. Use inside-bark measurements when possible.
3. Separate butt logs from upper logs because quality differs.
4. Match your rule to the local market or mill.
5. Apply realistic deductions instead of assuming every tree is clear and straight.
6. Keep a field notebook with species, grade notes, and defects.
7. Compare calculator estimates to actual sawn output over time to improve your own local recovery factors.

Authoritative references for timber measurement

For deeper reading on forest measurement, log scaling, and timber valuation, review these authoritative resources:

• U.S. Forest Service
• Penn State Extension
• University of Minnesota Extension

Final takeaway

To calculate board feet of a tree, measure diameter and merchantable length, choose a log rule, estimate each log section individually, and then apply waste deductions. The simple formula is useful for quick planning, while Doyle and Scribner provide more trade-oriented estimates. The most important point is consistency. Use the same rule, similar measuring practices, and realistic deductions every time. That is how you turn rough field measurements into dependable sawtimber estimates.