A board foot, also referred to as board feet, FBM, BF, or BDFT, describes the size of a piece of lumber before cutting it to its final size. Industry professionals, such as sawmill owners, rely on board footage to determine how much lumber they have.

How to Calculate Board Footage

If you own or operate a sawmill, lumberyard, or another business that involves lumber, you need to know how to calculate board footage. The mathematical formula is simple.

Thickness x Length x Width / 12 = Board Feet

For example, if you have a 2×4 that is 10 feet long, your formula for determining board feet is:

2 x 4 x 10 / 12 = 6.667 board feet

There are ways to determine board footage if you have multiple pieces of lumber. First, add the number of pieces you have to the beginning of the formula and then perform the same calculation for the total board feet.

If you have 84 of the ten-foot-long 2x4s that we already calculated the board footage on, your BDFT calculations look like this:

84 x 2 x 4 x 10 / 12 = 560 board feet.

The table below lists the board feet in a 1′ piece of lumber for each dimension:

Lumber Dimension Board Foot Measurement:

Why Should You Calculate Board Feet

Sawmills and lumber yards rely on board footage to determine how much lumber they have. It’s also common for these businesses to rely on board footage when setting prices.

The contractor you hire may provide a price for your construction project involving board feet.

For instance, your contractor may use board footage when determining how much lumber is needed for the sheathing layer on your roof. Other practical applications involve outdoor decking and sheathing on your home’s walls.

It is important to note that total board footage is not a linear measurement. Just because you have 2,000 board feet on hand doesn’t mean you have 2,000 linear feet of lumber.

Knowing how to calculate BDFT can give you a better idea of how much your home construction project should cost. You can use an online board foot calculator for an estimate. Using those tools and the formulas we’ve provided can give you a better understanding of project costs.