Board foot calculator for lumber and hardwood
Multiply thickness in inches by width in inches by length in feet and divide by 12. A 1×6 that is 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet. Multiply by the number of boards and by the price per board foot for the cost.
Inputs used by this calculator
Board Foot Calculator uses the fields below. The starting values reproduce the page example; replace them with values from the same units and time period before using the result.
| Input | Starting example | Accepted value | How it is used |
|---|---|---|---|
| Thickness (in) | 1 | 0.01 to 48 | Supplies the thickness (in) quantity used by the published equation or result breakdown. |
| Width (in) | 6 | 0.01 to 120 | Supplies the width (in) quantity used by the published equation or result breakdown. |
| Length (ft) | 8 | 0.01 to 100 | Supplies the length (ft) quantity used by the published equation or result breakdown. |
| Number of boards | 10 | 1 to 1000000 | Supplies the number of boards quantity used by the published equation or result breakdown. |
| Price per board foot ($) | 4.5 | 0 to 100000 | Supplies the price per board foot ($) quantity used by the published equation or result breakdown. |
What a board foot is
A board foot is a unit of lumber volume: a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. A 2×6 one foot long is also one board foot, and so is a 1×4 three feet long. Twelve board feet make one cubic foot.
The formula
With thickness and width in inches and length in feet, multiply all three and divide by 12. If every measurement is in inches, divide by 144 instead. The calculator multiplies by the number of boards for an order total.
board feet = T (in) × W (in) × L (ft) ÷ 12board feet = T × W × L (all in inches) ÷ 144Nominal versus actual sizes
A 2×4 from the lumberyard actually measures about 1.5 × 3.5 inches after drying and planing. Board feet for dimension lumber are traditionally figured on the nominal size, so a 2×4 × 8 ft counts as 5.33 board feet even though less wood is there. Enter nominal sizes to match a yard's tally, or actual sizes to estimate the real volume.
Hardwood quarters
Hardwood is sold by thickness in quarters of an inch: 4/4 (one inch), 5/4, 6/4, 8/4 and so on, usually measured rough before planing. Widths and lengths are often random, so dealers tally each board's board feet and add them up. Expect some waste when the rough board is planed to final size.
Pricing and comparing quotes
Price per board foot makes boards of different sizes comparable. To compare with a price per linear foot, divide it by the board feet in one foot of that board: a 1×6 has 0.5 board feet per linear foot, so $2.25 a linear foot equals $4.50 a board foot.
Adding a waste allowance
Knots, checks, defects and cutting losses mean you need more than the finished volume. Many woodworkers add 15 to 30% for hardwood projects, more for highly figured boards or tight-grain matching. Increase the number of boards or length to include it.
Board feet for common lumber sizes
| Nominal size | Actual size | Board feet per linear foot | Board feet in 8 ft |
|---|---|---|---|
| 1×4 | 0.75 × 3.5 in | 0.333 | 2.67 |
| 1×6 | 0.75 × 5.5 in | 0.5 | 4 |
| 1×8 | 0.75 × 7.25 in | 0.667 | 5.33 |
| 1×12 | 0.75 × 11.25 in | 1 | 8 |
| 2×4 | 1.5 × 3.5 in | 0.667 | 5.33 |
| 2×6 | 1.5 × 5.5 in | 1 | 8 |
| 2×8 | 1.5 × 7.25 in | 1.333 | 10.67 |
| 2×10 | 1.5 × 9.25 in | 1.667 | 13.33 |
| 2×12 | 1.5 × 11.25 in | 2 | 16 |
| 4×4 | 3.5 × 3.5 in | 1.333 | 10.67 |
Frequently asked questions
How do I calculate board feet?
Thickness (in) × width (in) × length (ft) ÷ 12. A 2×6 that is 10 feet long is 2 × 6 × 10 ÷ 12 = 10 board feet.
How many board feet are in a 2×4×8?
5.33 board feet on its nominal size: 2 × 4 × 8 ÷ 12.
How many board feet are in a cubic foot?
Twelve. A cubic foot is 1,728 cubic inches and a board foot is 144.
Do I use nominal or actual dimensions?
Lumberyards usually tally softwood on nominal sizes and hardwood on rough thickness. Use the same basis as the seller when comparing prices.
What does 4/4 mean in hardwood?
Four quarters of an inch, or 1 inch thick, usually before planing. 8/4 is 2 inches.
How do I convert price per linear foot to board foot?
Divide the linear-foot price by the board feet in one foot of that board. For a 1×8 (0.667 board feet per foot), $3 a linear foot is $4.50 a board foot.
What to keep in mind
Softwood dimension lumber is usually priced per piece or per linear foot and figured on nominal sizes; hardwood is sold by the board foot, usually on rough thickness. Check how your yard measures before comparing prices.
Results are rounded for display in US format, with money in dollars and cents; CSV exports keep full calculation precision. This is a calculation summary, not an official certificate.