HowMuchIt / Board feet
How do I calculate board feet?
Thickness in inches times width in inches times length in feet, divided by 12. Lumber yards sell hardwood this way; the calculator adds up the pieces.
Work out the board feet
| Step | How |
|---|---|
| One board foot | 144 cubic inches: 12 x 12 x 1 in |
| Board feet | thickness (in) x width (in) x length (ft) / 12 |
| Cubic feet | board feet / 12 |
| Hardwood thickness | in quarters: 4/4 = 1 in, 8/4 = 2 in |
Planed lumber is counted at its nominal size: a 2x4 counts as 2 by 4 inches though it measures about 1.5 by 3.5.
Nominal sizes and quarters
A board foot is a piece 12 inches wide, 12 long and 1 thick: 144 cubic inches, a twelfth of a cubic foot. Dimensional lumber is counted from its nominal size, so a 2x4 counts as 2 by 4 inches even though it measures about 1.5 by 3.5. Hardwood thickness comes in quarters of an inch: 4/4 is 1 inch rough, 8/4 is 2 inches.
Questions people ask
How many board feet in ten 8 ft 2x4s?
2 x 4 x 8 / 12 = 5.33 each: about 53.3 board feet.
Is a 2x4 really 2 by 4 inches?
No: about 1.5 by 3.5. Board feet still count it as 2 by 4.
Good to know
- A board foot is 144 cubic inches: a piece 12 inches wide, 12 inches long and 1 inch thick.1,2,3,4
- Board feet = thickness (in) x width (in) x length (ft) / 12.1,4
- One board foot is 1/12 of a cubic foot, so 12 board feet make one cubic foot.2,5
- Board feet of dimensional (planed) lumber are figured from the nominal size, so a 2x4 counts as 2 by 4 inches.1,3,4,5
- A nominal 2x4 actually measures about 1.5 by 3.5 inches.1,6
- Hardwood thickness is given in quarters of an inch: 4/4 is 1 inch rough, 8/4 is 2 inches.7,8
How we checked this page
Checked on October 27, 2026. We kept a fact only when two independent publishers agree, and each one is numbered to its sources below. Where sources give different numbers, we keep only what they share. We never write a price. This page was written with an AI assistant and checked against the sources below.
Sources
- Board Footage Calculator for Lumber Measurements, Today's Homeowner
- How Many? A Dictionary of Units of Measurement (B), Russ Rowlett, University of North Carolina at Chapel Hill
- Softwood Lumber Products Export Permit Fees Regulations (SOR/96-317), Justice Laws Website, Government of Canada
- Board Feet Chart and Calculator, The Engineering ToolBox
- Board foot, Wikipedia (unit definition)
- Softwood Lumber - Dimensions, The Engineering ToolBox
- Hardwood Lumber - Dimensions, The Engineering ToolBox
- Lumber, Wikipedia (unit notation)