Board Feet Calculator Log

Estimate log volume in board feet using exact solid wood volume and common log scale rules. Enter small-end diameter, log length, quantity, and your preferred rule to compare outputs for sawmill planning, timber sales, and rough lumber estimation.

Includes exact volume plus Doyle, Scribner, and International comparisons

Expert Guide to Using a Board Feet Calculator for Logs

A board feet calculator log tool helps estimate how much lumber a log can produce before it reaches the mill. For buyers, woodland owners, portable sawmill operators, and woodworkers, understanding log volume in board feet is one of the most practical skills in forestry and lumber planning. A board foot is a unit of lumber volume equal to a board that is 12 inches long, 12 inches wide, and 1 inch thick. Because logs are round and boards are rectangular, calculators use formulas or scale rules to estimate equivalent board feet.

The calculator above gives you both an exact solid wood estimate and comparisons using well known rules such as Doyle, Scribner, and International 1/4. These methods often produce different answers because each one makes different assumptions about taper, slab loss, edging, and saw kerf. That difference matters. A landowner negotiating stumpage, a sawyer pricing custom cuts, and a builder estimating timber stock can all arrive at different numbers if they are not using the same rule.

If you are new to log scaling, think of this page as both a calculator and a field guide. You can quickly estimate volume for one log or many logs, compare scale systems, and understand why your number may not match someone else’s tally sheet.

What does board feet mean for a log?

Board feet in standing timber and sawlogs is a way of translating a round log into the lumber volume that might be sawn from it. There are two broad approaches:

• Exact solid wood volume: This uses the log’s diameter and length to calculate the cylindrical volume and then converts it into board feet. It tells you how much wood is physically present.
• Log scale rules: These estimate recoverable lumber after accounting for waste, saw kerf, and practical mill losses. That is why scale rule values are typically lower than exact solid volume.

Neither method is universally “right” in every situation. Exact volume is useful for understanding total wood content. Scale rules are more useful when discussing sales contracts, mill procurement, and expected lumber recovery.

The basic formula behind exact board foot log volume

If diameter is measured in inches and length is measured in feet, the exact solid wood volume of a log treated as a cylinder can be estimated with this formula:

Board feet = 0.06545 × diameter² × length

This is equivalent to using the cylinder volume formula and converting cubic feet to board feet. The exact calculator result on this page uses that relationship, then adjusts by quantity and any quality factor you choose. The milling loss percentage can also show a practical net estimate after sawdust, slabs, edging, and trimming.

Common log scale rules and why they differ

The most common North American log rules are Doyle, Scribner, and International 1/4. Their outputs can differ substantially, especially on small logs. Here is what makes each one distinctive:

• Doyle: Often underestimates small logs because it assumes relatively large slab loss. It becomes more favorable on larger diameters. Many timber buyers still reference Doyle in certain regions.
• Scribner: Based on diagrams of boards sawn from a log. It is often considered more balanced than Doyle, but it still simplifies real milling conditions.
• International 1/4: Designed to account more realistically for taper and a quarter inch saw kerf. Many forestry professionals consider it more consistent across a range of diameters and lengths.

If your local market quotes stumpage or delivered log prices by board foot, always confirm the exact scale rule being used. A 500 board foot difference across a truckload can materially change the value.

Example Log	Exact Solid Volume	Doyle Rule	Scribner Rule	International 1/4 Rule
12 in diameter × 8 ft length	75 BF	32 BF	41 BF	58 BF
16 in diameter × 12 ft length	201 BF	108 BF	128 BF	151 BF
20 in diameter × 16 ft length	419 BF	256 BF	284 BF	322 BF
24 in diameter × 12 ft length	453 BF	300 BF	318 BF	356 BF

The table above illustrates a pattern seen in real scaling work: exact wood content is highest, Doyle is often lowest, and International usually falls in between exact volume and more conservative rules. The gap is especially important on small logs where slab and kerf losses consume a larger share of the wood.

How to measure a log correctly

1. Measure the small-end diameter inside bark if possible. This is the most common reference point for log scaling. Measure across the small end at the shortest diameter, then at right angles if needed for an average.
2. Measure usable length in feet. Commercial lengths often follow standard increments, but actual cut lengths may include trim allowance.
3. Count the number of logs. If all logs are close in size, one average input may be enough for rough planning. For selling timber, each log should ideally be scaled individually.
4. Select the proper rule. Use the rule your buyer, mill, or local forestry office references.
5. Adjust for quality and loss. Crook, sweep, excessive taper, butt flare, rot, and checks can reduce usable yield.

Why milling loss matters

Many people assume a log with 300 board feet of solid wood should automatically produce 300 board feet of lumber. In practice, that does not happen. Some volume is lost to:

• Slabs removed to square the log
• Saw kerf converted to sawdust
• Edging and trimming defects
• Wane and grade restrictions
• Drying shrinkage in finished products

That is why this calculator includes an estimated milling loss input. A clean, straight log processed on optimized equipment may recover well. A knotty, tapered, or crooked log may recover much less. For rough planning, a 10 percent to 15 percent loss assumption is common for showing the difference between gross and practical net output, but actual recovery varies by species, mill setup, target dimensions, and operator skill.

Real world factors that change board foot estimates

A board feet calculator log result is only as reliable as the field measurements and assumptions behind it. The following variables commonly affect outcomes:

• Taper: Logs are not perfect cylinders. Large-end and small-end diameters can differ significantly.
• Bark thickness: Diameter inside bark is a better measure than outside bark when estimating wood content.
• Defects: Heart rot, ring shake, checks, metal, and severe knots reduce recoverable lumber.
• Species: Dense hardwood and straight softwood logs can behave differently in milling and grading.
• End use: Sawing for wide live edge slabs, timbers, or narrow framing boards changes recovery patterns.
• Mill technology: Thin kerf band mills usually recover more than older circular saw setups.

Log Feature	Typical Effect on Recoverable Board Feet	Planning Note
Straight log with low taper	Higher recovery, often 5 percent to 12 percent better than irregular logs of similar size	Usually produces more full length boards and less edging waste
Crooked or swept log	Lower recovery due to alignment loss and trim waste	May still be valuable for short stock or specialty cuts
Thin kerf band mill	Can improve lumber recovery by several percentage points compared with wider kerf systems	Especially noticeable on smaller diameter logs
Heavy bark or butt flare	Reduces usable wood compared with outside bark measurements	Prefer inside bark diameter when possible

When to use exact solid volume instead of a scale rule

Exact solid volume is useful when your goal is physical wood content rather than a traditional trade scale. For example, you may want exact board feet if you are:

• Estimating rough sawn timber for a personal building project
• Comparing one log to another before slab milling
• Approximating total wood resource on site
• Converting between cubic measure and board measure for inventory planning

In contrast, if you are selling logs into an established regional market, the market rule usually matters more than the exact cylinder volume because the buyer and seller need the same commercial language.

How foresters and mills use these numbers

Board foot estimates influence more than simple volume. They are tied to pricing, trucking, harvest planning, and sawing strategy. Foresters use scaling to estimate stand value and compare management options. Mills use board foot counts to budget production, labor, and lumber output. Independent sawyers use them to quote custom jobs. Woodworkers use them to decide whether a log is worth transporting and milling.

For example, a portable mill operator might compare a 16 inch by 12 foot oak log and an 18 inch by 10 foot pine log. Even if one appears larger at first glance, the actual board foot potential may shift once diameter, taper, defect, and target product are considered. Good scaling leads to better project economics.

Helpful authoritative resources

If you want deeper technical guidance on log scaling and timber measurement, these sources are excellent places to start:

• USDA Forest Service for timber measurement, forest products, and sawmill information.
• Penn State Extension for woodland management and log scaling education.
• Purdue Extension for forestry and wood products guidance.

Frequently asked questions about board feet calculator log tools

Is board foot the same as cubic foot? No. One board foot equals 1/12 of a cubic foot. Board feet is a lumber-specific measure, while cubic feet measures total volume.

Why is the exact result higher than Doyle or Scribner? Exact volume shows the wood physically present in a cylindrical form. Scale rules estimate recoverable lumber after practical losses.

What diameter should I use? In most cases, use the small-end diameter inside bark for sawlog scaling. If your local market specifies another method, follow that standard.

Can I use one average diameter for a pile of logs? For a rough estimate, yes. For accurate appraisals, scale each log separately because small differences in diameter create large changes in board feet.

Does species affect the board foot formula? The core geometry does not, but actual recovery and quality do. Species affects grade, defect patterns, shrinkage, and sawing strategy.

Practical tips for better estimates

• Measure twice if the log is near a price threshold.
• Use inside bark diameter whenever possible.
• Separate premium straight logs from lower grade material before estimating value.
• Track local buying conventions because some markets still strongly favor one rule over another.
• Remember that longer logs are not always more efficient if sweep, taper, or defect increases.
• For custom sawing, compare gross board feet to net expected output after milling loss.

Bottom line

A quality board feet calculator log tool gives you a fast and informed estimate of lumber potential, but the best results come from accurate measurements and the right scale rule. Use exact solid volume when you want a pure geometric wood estimate. Use Doyle, Scribner, or International when you need a market-oriented or mill-oriented scaling approach. By comparing all of them in one place, you can make better decisions about timber sales, portable milling, project budgeting, and lumber recovery.

Use the calculator above to test different diameters, lengths, and quantities. You will quickly see how strongly diameter drives board foot yield, why small logs often scale conservatively, and why quality adjustments can matter almost as much as size.