What Is Board Foot?
A board foot is a unit used to measure the volume of lumber. It helps buyers and sellers know how much wood is in boards of different sizes.
Definition
One board foot is the volume of a piece of wood that is:
- 1 foot long
- 1 foot wide
- 1 inch thick
In other words, it is a way to measure how much solid wood is in a board, not just how long it is.
Mathematically, 1 board foot equals:
- 144 cubic inches of wood
- 1/12 of a cubic foot of wood
- about 2.36 liters of wood
History / Origin
The board foot started in North America as lumber cutting and selling became a big business. Saw mills and timber companies needed a simple way to measure how much wood they produced and sold.
People who cut trees into boards used the size of a common board as a base measure. A board that was 1 inch thick, 12 inches wide, and 12 inches long became the standard size for 1 board foot.
This system made it easier to pay loggers, price lumber, and compare loads of wood, even when the boards were not all the same length or width.
Symbol & Abbreviation
Several short forms are used for board foot. All of these usually mean the same thing:
- bd ft
- BF
- BDFT
- FBM (means Foot Board Measure)
For example, a lumber bill might say 250 bf or 250 bd ft. That means 250 board feet of wood.
Current Use Around the World
The board foot is most common in:
- United States
- Canada
- Some parts of Central America
In these places it is widely used by:
- sawmills
- lumber yards
- carpenters and builders
- furniture makers
- foresters and log buyers
Many other countries use the metric system instead, and measure lumber volume in cubic meters. Still, people who trade wood worldwide often need to understand both board feet and metric units so they can compare prices and amounts.
Example Conversions
You can find board feet from the size of a board in inches with this simple formula:
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12
Here are some clear examples.
Example 1
Board size: 1 inch thick, 12 inches wide, 12 inches long
- Length in feet: 12 in ÷ 12 = 1 ft
- Board feet = (1 × 12 × 1) ÷ 12 = 1 board foot
Example 2
Board size: 2 inches thick, 4 inches wide, 8 feet long
- Board feet = (2 × 4 × 8) ÷ 12
- 2 × 4 × 8 = 64
- 64 ÷ 12 ≈ 5.33 board feet
Example 3
Board size: 1.5 inches thick, 6 inches wide, 10 feet long
- Board feet = (1.5 × 6 × 10) ÷ 12
- 1.5 × 6 × 10 = 90
- 90 ÷ 12 = 7.5 board feet
Convert board feet to cubic feet
- 1 board foot = 1/12 cubic foot
- To get cubic feet, divide board feet by 12
Example: 120 board feet ÷ 12 = 10 cubic feet.
Convert board feet to cubic meters (approximate)
- 1 board foot ≈ 0.00236 cubic meter
Example: 500 board feet × 0.00236 ≈ 1.18 cubic meters.
Related Units
Units that are often used together with or instead of board feet include:
- Linear foot (foot of length) measures how long a board is, but not how thick or wide it is.
- Square foot measures area, for example the face of a board, but does not include thickness.
- Cubic inch a very small volume unit used in the formula for board feet.
- Cubic foot a larger volume unit. There are 12 board feet in 1 cubic foot.
- Cubic meter metric volume unit that many countries use for lumber instead of board feet.
FAQs
What is a board foot in simple words?
A board foot is a way to measure how much solid wood is in a board. It is the same as a piece of wood 1 foot long, 1 foot wide, and 1 inch thick.
Why do lumber yards use board feet?
Lumber yards use board feet because it lets them compare and price boards of many different sizes by one common volume unit, so buying and selling is more fair and clear.
Is board foot a metric unit?
No. The board foot is part of the old imperial and US system. Metric systems use cubic centimeters, cubic decimeters, and cubic meters instead.
How do I quickly estimate board feet?
Measure thickness and width in inches, length in feet, multiply thickness by width by length, then divide by 12. The answer is the number of board feet.
Can two boards with the same board feet have different shapes?
Yes. A short thick board and a long thin board can have the same total volume of wood, so they can be the same number of board feet even if they look different.
Do all countries use board feet?
No. Board feet are mostly used in the United States and Canada. Many other countries prefer cubic meters or other metric volume units for lumber.
Is board foot used only for sawn boards?
It is mainly used for sawn lumber, but it can also be used to estimate the usable wood volume in logs before they are cut, using special log rules and tables.
