Board Feet From A Log Calculator

Estimate log volume fast with common log rules used by sawmills, foresters, landowners, and timber buyers. Enter your small-end diameter, log length, quantity, and preferred rule to calculate board feet from a log and compare yield assumptions visually.

Interactive Log Board Foot Calculator

Expert Guide to Using a Board Feet From a Log Calculator

A board feet from a log calculator helps estimate how much lumber a round log may produce before the log reaches the mill. This estimate is central to timber cruising, stumpage sales, sawmill purchasing, woodlot planning, and rough budgeting for custom sawing. While the output looks simple, the number reflects a log scaling rule, the measured diameter, the measured length, and any deductions for defect. If you want better forestry decisions, better pricing conversations, and better yield expectations, understanding what the calculator is doing matters.

At its core, a board foot is a volume measure equal to a board that is 12 inches wide, 12 inches long, and 1 inch thick. That equals 144 cubic inches, or exactly 1/12 of a cubic foot. The challenge with logs is that they are round, tapered, and imperfect. A sawmill cannot recover every cubic inch as finished lumber because slabs, saw kerf, edging, trim loss, shrinkage, and defects all reduce usable output. That is why the forest products industry developed log rules such as Doyle, Scribner, and International 1/4-inch to estimate recoverable lumber rather than pure solid wood volume.

Quick takeaway: the same log can produce very different board foot values depending on the log rule selected. That does not always mean one number is wrong. It usually means each rule makes different assumptions about taper, slab loss, and kerf.

What the calculator measures

This calculator uses the small-end diameter inside bark and the log length in feet. Those are the two most common field measurements used in basic log scaling. You can also apply a percentage deduction for defect and multiply by the number of logs. The species selector is included for context because species often affects marketing, grade, and value, but the actual board foot formula here is driven primarily by diameter, length, and rule.

• Diameter: Usually measured at the small end of the log inside bark for scaling purposes.
• Length: Merchantable log length, often expressed in standard increments such as 8, 10, 12, 14, 16, 18, or 20 feet.
• Defect: Crook, rot, sweep, shake, holes, or breakage that lowers recoverable lumber volume.
• Rule: The mathematical system used to convert the measured log into estimated board feet.

How board foot log rules differ

The three most recognized rules in North America are Doyle, Scribner, and International 1/4-inch. Each has historical importance, regional use patterns, and known biases. If two buyers quote the same log using different scales, the board foot total can change substantially, especially for smaller diameters.

1. Doyle Rule: Very common in parts of the eastern and central United States. It tends to underestimate small logs and becomes more favorable as diameter increases.
2. Scribner Rule: Based on diagramming boards within a log cross section. It is often considered more moderate than Doyle for many diameters.
3. International 1/4-inch Rule: Widely viewed as one of the more technically realistic traditional log rules because it incorporates taper and a saw kerf assumption.

For landowners, the most practical lesson is this: always ask what scale is being used. A quoted stumpage price without a stated rule is incomplete. A higher price per thousand board feet can still produce a lower total payment if the scale rule yields fewer board feet.

Sample comparison table for common logs

The table below shows example outputs for several common log sizes. These values are representative calculator results using traditional formulas and no defect deduction. They illustrate why log rule selection matters.

Small-End Diameter	Length	Doyle BF	Scribner BF	International 1/4 BF
12 in	12 ft	48	61	76
14 in	16 ft	100	123	159
16 in	16 ft	144	166	207
18 in	16 ft	196	220	263
20 in	20 ft	320	402	476

Notice the spread between Doyle and International on smaller and medium logs. That gap is one reason foresters often emphasize comparing bids on the same basis. If your woodlot inventory was cruised in International 1/4-inch but your local buyer quotes Doyle, you need an apples-to-apples conversion or a clear explanation before comparing offers.

Important conversion statistics every user should know

Even though board feet are common in sawtimber transactions, understanding how the unit relates to physical wood volume improves planning. The statistics below are fixed conversion facts that help put log scaling in context.

Measure	Equivalent	Why It Matters
1 board foot	144 cubic inches	Base definition of board foot volume
1 board foot	1/12 cubic foot	Useful for rough volume comparisons
100 board feet	8.33 cubic feet	Helps estimate truck and stack volume
1,000 board feet	83.33 cubic feet	Common trade unit known as MBF

Why the same log does not equal the same lumber in every mill

A board feet from a log calculator is a scaling tool, not a guarantee of finished output. Actual recovery varies by mill equipment, breakdown strategy, target products, species, log straightness, and sawing skill. Modern mills with thin-kerf systems, optimized scanners, and strong edging strategies may recover more saleable lumber than older mills from the same average log basket. Custom sawyers may also prioritize wide live-edge slabs or specialty cuts that change apparent yield compared with a commodity grade mill.

This is also why some mills discuss overrun or underrun. Overrun means the mill recovered more lumber tally than the scale suggested. Underrun means less. The concept reminds users that log scale is a prediction based on assumptions, not a direct measurement of future boards stacked on stickers.

How to measure a log correctly before using the calculator

1. Measure the small-end diameter at the narrow end of the log.
2. Use the measurement inside bark if your market or local scaling practice requires it.
3. Measure the merchantable length in feet, accounting for trim allowances as needed.
4. Inspect for defects such as rot pockets, heavy sweep, crook, fire scar, or severe checking.
5. Select the same scale rule used in your market area or by your buyer.
6. Apply a defect deduction only when you have a reasonable field estimate.

One of the easiest mistakes is measuring bark-to-bark and entering that number as inside bark. Thick-barked species can make the log appear more voluminous than its actual usable wood. Another common mistake is using the large-end diameter. Traditional log scale methods generally rely on the small end because it better reflects the limiting cross section for sawn lumber.

When to use Doyle, Scribner, or International 1/4-inch

Use the rule that matches your local timber market first. Market convention often matters more than academic preference in real transactions. In some states, hardwood buyers still commonly use Doyle because the regional pricing system is built around it. In other areas, especially where foresters emphasize more technically balanced estimates, International 1/4-inch may be more common. Scribner remains relevant in several western and mixed-use markets.

• Use Doyle if that is the prevailing rule in your hardwood market and you need a practical pricing estimate.
• Use Scribner when your mill, timber buyer, or sale documents specify it.
• Use International 1/4-inch when you want a rule often regarded as more consistent across log sizes.

Practical example

Suppose you have five oak logs, each 16 inches in small-end diameter and 16 feet long, with an estimated 8% defect deduction. Under Doyle, the gross scale is about 144 board feet per log, or 720 board feet total. After an 8% deduction, the net estimate becomes roughly 662 board feet. Under International 1/4-inch, the same basket could scale near 207 board feet per log, or about 1,035 board feet gross, then approximately 952 board feet net after the same deduction. That difference can materially affect bid comparisons, harvest planning, and transport economics.

How to use this calculator for timber sale planning

If you are preparing for a selective cut, thinning, or final harvest, this calculator works best as a screening and communication tool. Use it to estimate volumes by log, compare rules, and build a rough picture of total sawtimber output. Then validate those assumptions with a consulting forester, procurement forester, or professional timber cruiser before making financial decisions.

For a more reliable sale estimate:

• Sample multiple logs across species and diameter classes.
• Separate veneer-quality stems from ordinary sawlogs.
• Track defects by tree or stand area.
• Use the same log rule in your inventory and in all bid requests.
• Document whether scaling is done roadside, at the landing, or at the mill.

Common mistakes that distort board foot estimates

• Mixing up board feet and cubic feet.
• Using outside-bark measurements when inside-bark scale is expected.
• Ignoring trim, taper, and defect.
• Comparing bid prices quoted under different scale rules.
• Assuming every species yields identical recovery and grade value.
• Relying on one log example to represent an entire tract.

Authority sources for timber measurement and log scaling

For deeper study, review educational and agency materials from established forestry sources. Helpful references include the U.S. Forest Service, timber measurement guidance from Penn State Extension, and forestry measurement resources from the University of Maryland Extension. These sources help explain field measurement, merchantable volume, and the broader context of timber valuation.

Final perspective

A good board feet from a log calculator gives you a fast, structured way to estimate sawlog volume, but the most accurate use comes from pairing the math with sound measurement habits and the correct local log rule. Treat the result as a professional estimate, understand the assumptions behind it, and use consistent scaling when comparing buyers or planning a harvest. If you do that, this tool becomes much more than a quick number generator. It becomes a practical decision aid for forestry, milling, and land stewardship.