Log Board Foot Calculator

Estimate the lumber in a log using the Doyle, Scribner or International ¼-inch log rule. Add logs to a tally to total a load and estimate its value.

Log Rule
Use the rule your buyer or mill scales by. All three are shown in the results.
Measure the small end, inside the bark. Average two measurements if it isn't round.
$
Logs are usually bought per thousand board feet (MBF) on a named log rule, such as $400 per MBF Doyle.
144
Board Feet, Doyle
Per log
144 BF
Thousand board feet
0.144 MBF
Value
Add a price to estimate
Same Log Under Each Rule

Log Tally

Totals use the log rule and price selected above. Logs you add are saved in this browser.

LogsDiameterLengthDoyleScribnerInt'l ¼″Remove
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How Log Rules Estimate Board Feet

A log rule estimates how many board feet of lumber a sawmill can cut from a log, based on its small-end diameter and length. Because a round, tapered log has to be squared up and sawn into boards, some wood is always lost to slabs, edgings and sawdust. Each rule makes different assumptions about that loss, so the same log scales differently under each one.

Doyle

Board feet = (D − 4)² × L ÷ 16

The Doyle rule deducts 4 inches from the diameter to allow for slabs, which is far too much for small logs. It heavily underestimates logs under about 20 inches and slightly overestimates very large ones. It's the rule most commonly used for hardwood logs in the southern United States.

Scribner

Board feet ≈ (0.79D² − 2D − 4) × L ÷ 16

Scribner was built from diagrams of the 1-inch boards that fit inside circles of each diameter, with a ¼-inch saw kerf. It doesn't account for taper, so it underestimates logs longer than 16 feet. The Scribner Decimal C version, which rounds to the nearest 10 board feet, is common on the West Coast and for southern pine. The formula above closely approximates the published tables.

International ¼-Inch

Each 4-ft section = 0.905 × (0.22D² − 0.71D)

The International rule treats the log as 4-foot sections, adding ½ inch of taper to the diameter for each section, and allows for a ¼-inch saw kerf. It's the most accurate of the three at predicting what a mill actually saws, and it's used for timber sales on eastern national forests and many state forests. Published tables round to the nearest 5 board feet.

Board Feet in a 16-Foot Log

Small-End DiameterDoyleScribnerInternational ¼″
8″163139
10″365565
12″648697
14″100123136
16″144166181
18″196216232
20″256272290
22″324334354
24″400403424
26″484478501
28″576559585
30″676647674
32″784741770
34″900841873
36″1,024948981

Measuring and Selling Logs

Diameter is measured inside the bark at the small end, and scalers usually drop fractions to the nearest inch below. Length is usually scaled in whole feet, with 4 to 6 inches of extra trim left on the log that isn't counted. Deductions for rot, splits, sweep and other defects are taken from the gross scale to get the net scale.

Always confirm which rule a buyer uses before comparing prices. A price of $400 per MBF Doyle can pay more or less than $350 per MBF International, depending on the size of your logs.