The board foot calculator below will calculate the board feet and volume (cubic ft) of any piece or pieces of wood.
Board feet is a measure of volume. Because hardwood lumber can vary wildly in thicknesses and widths, board feet is a common unit of measurement that lumber mills and yards use for calculating a given quantity of (usually) hardwood lumber.
More information on the history of the use of board feet can be found here.
Also, check out the lumber weight calculator if you want to estimate lumber weights and the plywood weight calculator if you want to estimate plywood weights.
BOARD FOOT CALCULATOR
How To Use This Calculator
Lumber Size
First, choose your lumber size. You can either choose from a list by nominal dimensions or enter in the actual dimensions manually. Here is a table showing nominal sizes vs actual sizes for reference:
| Nominal Size (inches) | Actual Size (inches) |
|---|---|
| 1 x 2 | 3/4 x 1 1/2 |
| 1 x 3 | 3/4 x 2 1/2 |
| 1 x 4 | 3/4 x 3 1/2 |
| 1 x 6 | 3/4 x 5 1/2 |
| 1 x 8 | 3/4 x 7 1/4 |
| 1 x 10 | 3/4 x 9 1/4 |
| 1 x 12 | 3/4 x 11 1/4 |
| 2 x 2 | 1 1/2 x 1 1/2 |
| 2 x 3 | 1 1/2 x 2 1/2 |
| 2 x 4 | 1 1/2 x 3 1/2 |
| 2 x 6 | 1 1/2 x 5 1/2 |
| 2 x 8 | 1 1/2 x 7 1/4 |
| 2 x 10 | 1 1/2 x 9 1/4 |
| 2 x 12 | 1 1/2 x 11 1/4 |
| 4 x 4 | 3 1/2 x 3 1/2 |
| 4 x 6 | 3 1/2 x 5 1/2 |
| 6 x 6 | 5 1/2 x 5 1/2 |
| 5/4 x 6 | 1 x 5 1/2 |
| 6/4 x 6 | 1 5/16 x 5 1/2 |
Next, enter the length of the lumber in question followed by the number of pieces of that lumber.
Board Foot Equation and Calculation
To calculate board feet, the equation is as follows:
Board Feet = (Width (inches) x Thickness (inches) x Length (FEET)) / 12
Note that if you select from the list of nominal dimensions in the calculator above, the board feet and volume will be calculated using the nominal dimensions instead of the actual dimensions.
For example, a 1×12 that is 1 foot long would be calculated as:
Board Feet = ((1x12x1)/12) = 1 board foot
This may seem confusing, as the actual dimensions of a 1×12 are 3/4 x 11 1/4. This would give an “actual” board footage of:
Board Feet = ((3/4×11.25×1)/12) = 0.703 board feet
The bottom line is lumber mills and yards use nominal dimensions to calculate board feet when quantifying nominally sized wood and actual dimensions when quantifying irregular/random sized wood.