Board Feet 101: How to Calculate Lumber Volume
Updated: Apr 26
Board Foot Calculator
This bf calculator will help you determine the total amount of board feet given the length, width and thickness of a board. Enter the length in feet, inches or both.
Add the cost per board foot to help you determine how much a given amount of board feet will cost.
If you're a woodworker, you've probably heard the term "board foot" thrown around. But what exactly is a board foot (bf), and how is it calculated? In short, a board foot, primarily used when discussing hardwoods, is a unit of measurement that identifies the total volume of wood in a board. One board foot is equivalent to 144 cubic inches of wood or a board that is:
12 inches long x
12 inches wide x
1 inch thick
It's a crucial concept to understand if you want to accurately estimate the amount of lumber you need for your next project. In this article, I'll explain how board feet are calculated and provide you with a simple board foot calculator to make the process even easier.
How are Hardwoods Measured
Hardwoods are measured in board feet, unlike construction soft lumber which is expressed in its nominal form such as a 2x4 or a 2x6. However, if you look in the hardwood section of the big box store, you are likely to find their stock priced in linear feet (lf). This is to simplify pricing for the every day customer, but if you look closer, their hardwoods are still based on board feet.
Take these two poplar boards for example. One is 3 in. wide and the other is 6 in. wide.
With those dimensions, it will take 4 linear feet (lf) of the 1x3 to get a full board foot at that width and thickness. 4 lf x $1.75 = $7
It will take 2 linear feet of the 1x6 to get a full board foot. Since it is twice as wide, you need half the length for the same volume or 144 cubic inches of wood. 2 lf x $3.51 = $7.02
It is safe to say that this store has poplar hardwood priced at about $7 per board foot. If you are comparing pricing to a local saw mill, it is important to note the big box stores have surfaced on all 4 sides (S4S) while you are likely getting rough lumber or S2S from the saw mill, but at a much cheaper price.
Board Foot Calculator
This bf calculator will help you determine the total amount of board feet given the length, width and thickness of a board. Enter the length in feet, inches or both.
Add the cost per board foot to help you determine how much a given amount of board feet will cost.
How to Calculate Board Feet
Calculating board feet can be done without a wood calculator by following a simple formula.
Start by measuring the length, width, and thickness of the board in inches.
Then, multiply these dimensions together to find the total volume in cubic inches.
Finally, divide the total volume by 144 to get the number of board feet.
Don't forget! It is essential to convert all measurements to inches before doing the calculations.
With this method, you can easily estimate the amount of lumber you need for your next project without any specialized tools or equipment.
Here are three boards at various lengths, thicknesses and widths to illustrate how each dimension can impact the overall volume of wood. Board B is half as long as A, but twice as thick - both are still 144 cubic inches, thus 1 bf.
Example: | A | B | C |
Length: | 12" | 6" | 8' (or 96") |
Width: | 12" | 12" | 6" |
Thickness: | 1" | 2" | 1.5" |
Total Cubic Inches: | 144 | 144 | 864 |
Total Board Feet: | 1 | 1 | 6 |
Board Foot Formula
Length (inches) x Width (inches) x Thickness (inches) / 144 = Total BF
-or-
Length (feet) x Width (inches) x Thickness (inches) / 12 = Total BF
To obtain the board feet of your hardwood, measure the length, width and thickness.
The length of this board is 8 feet and 2-1/2 inches
The width is 5 inches
The thickness is 1-1/2 inches
The cost was $3.50 bf
Let's enter that into the board ft calculator to determine how many bf and the total cost of this board:
This board is 5.13 board feet and at $3.50 bf, it would cost $17.96.
I hope this article has been informative and helpful in understanding board feet and how to calculate them. If you have any questions or comment