How to Calculate Board Feet
Understanding a Board Foot and How to Calculate It
We get a lot of questions sent to us. Some are much more common than others.
Three of the more popular questions are:
- What is a board foot?
- Why isn’t hardwood lumber sold like pine in sizes such as 1×4, 1×6, 2×4?
- How do you calculate board feet?
We thought it’d be helpful if we broke these questions down. Here is everything you need to know:
What is a Board Foot?
A board foot is the unit of measure hardwood lumber is sold in. The easiest way to explain board footage is it’s a measure of volume. It is very similar to a square foot, but a board foot accounts for the thickness of the material. If you know how to measure square feet, you’re halfway there!
One board foot is equivalent to 12 inches wide x 12 inches long x 1 inch thick. This can be in any configuration, but the volume of the lumber has to be the same.
Why Isn’t Hardwood Lumber Sold Like Pine?
The shortest answer to this question is hardwoods and softwoods have different uses. Softwoods are primarily used for construction applications. When on a construction site, the piece of lumber goes straight from the bundle to being used in the construction project. There is no need to rip the boards to size, and that’s what dimensional lumber (2×4, 2×6, 1×4, 1×6, etc.) is designed to do.
But hardwoods are primarily used for flooring, millwork, moulding, cabinetry, furniture, windows, and doors. For most of these cases, the lumber needs to be further machined; ripped and chopped to size. That said, there is no need to cut the lumber to a standard size if the lumber is just going to get resized anyway. Hardwood lumber is sold with random width and length boards. The minimum size board is 3 inches wide by 4 feet long.
There are some other big differences between hardwoods and softwoods that also contribute to this. We cover those differences in our blog, “Hardwoods vs. Softwoods: What’s the Difference.”
How Do You Calculate Board Feet?
There are a couple of different ways to calculate board feet. Here are some different board foot calculations:
The first is by measuring in inches. Simply measure the length, width, and thickness of the board in inches. Then use this formula:
Width in inches x length in inches x thickness in inches / 144 = Board feet
Another way to calculate board feet is by measuring the width and thickness in inches and the length in feet. For this method, you can use this formula:
Width in inches x length in feet x thickness in inches / 12 = Board feet
The last practical way to measure board feet is by finding the square footage, and then multiplying that by the thickness. You can use this formula for this method:
Width in feet x length in feet x thickness in inches = Board feet
Is There Anything Else I Should Know About Board Feet?
Thickness can be a bit tricky. When calculating board feet, you should use the nominal thickness, not the actual thickness. Typically, the nominal thickness is based on every quarter of an inch with the minimum thickness being 1 inch. Round the thickness up to the nearest quarter of an inch. For example, if you had a ¾ inch board, you would use 1 inch thickness for calculating board feet. If you had 1 7/16 inch board, you would use 1 ½ inch for thickness.
Typically board footage is sold by the closest whole board foot. This means that if a board has 3.4 board feet, you will pay for only 3 board feet. But if a board has 3.6 board feet, you will pay for 4 board feet.