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Board Feet Calculator
Last updated: May 31, 2026
Written by Blake Boege
A board feet calculator computes the volumetric measurement of lumber where one board foot is equal to 144 cubic inches. The formula multiplies the nominal thickness and width in inches by the length in feet, dividing by twelve. It is the standard unit of measurement used by carpenters, contractors, and lumberyards to price and purchase hardwood and rough-sawn lumber.
Compute the total volume of lumber in board feet and estimate project material costs.
Quick Answer
Calculate the volume of lumber in board feet. Enter the thickness, width, length, and quantity of your boards to find total board feet.
Nominal thickness in inches (1, 2, 4/4, 5/4, 8/4 boards). · e.g. 1
Nominal width in inches. · e.g. 6
Length unit
e.g. 8
Number of pieces with these dimensions. · e.g. 10
Leave blank to skip the cost estimate. · e.g. 4.25
Board foot is a lumber volume unit equal to a 1 in × 12 in × 12 in block. The formula uses nominal dimensions.
10 pieces
40
4 BF per piece
Add a small waste allowance (5 to 10 percent) when ordering if you plan to rip, joint, or trim the lumber.
Examples
Five 2" x 6" boards, 10 feet long
10 board feet per piece, 50 board feet total
Ten 1" x 4" boards, 8 feet long
2.67 board feet per piece, 26.67 board feet total
How it works
Formula for Board Feet
The standard volume formulas for calculating board feet are:
When length is in feet · BF = (Thickness in × Width in × Length ft) ÷ 12
When length is in inches · BF = (Thickness in × Width in × Length in) ÷ 144
For a more singular look or detailed explanations on wood calculations, visit our standard board foot calculator.
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Frequently asked questions
Board feet are units of volume used in the lumber industry to measure wood. One board foot is equivalent to a volume of 144 cubic inches (typically represented as a board 1 inch thick, 12 inches wide, and 12 inches long).
To calculate board feet, multiply thickness (inches) × width (inches) × length (feet), then divide by 12. If length is measured in inches instead of feet, divide the product of all three dimensions by 144.
Hardwoods and rough-sawn lumber are sold by nominal size (their dimensions before drying and surfacing). A board that is nominally 1 inch thick may measure only 3/4 inches thick after planing, but is still billed using the nominal 1-inch thickness for board feet calculations.
Yes, you should typically add a waste factor of 10% to 20% to your total board feet requirements. This covers cutting loss, knots, splits, and grain matching during your carpentry or woodworking project.
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