Board Foot Calculator
Instantly calculate the total board feet (BF) and estimated lumber cost for your woodworking or construction project.
uying hardwood from a lumber yard can be a confusing experience, especially if you are used to buying standard dimensional lumber (like 2x4s) from a big-box home improvement store. Instead of paying per piece or per “linear foot,” rough-sawn hardwoods and exotic woods are sold by volume. This measurement is called a Board Foot (BF).
A board foot represents exactly 144 cubic inches of wood. Our free Board Foot Calculator takes the mental math out of your next woodworking or carpentry project. It instantly calculates your total board feet and estimates your exact project cost based on your local lumber yard’s pricing.
How to Use the Board Foot Calculator
We designed this tool to be as frictionless as possible for your mobile phone while standing right in the lumber aisle:
- Enter the Thickness: Input the thickness of your board in inches (e.g., 1 or 1.5).
- Enter the Width: Input the width of your board in inches (e.g., 6).
- Enter the Length: Input the length of your board. Use the dropdown menu to select whether your measurement is in Feet or Inches.
- Add Quantity & Price (Optional): If you are buying multiple identical boards, change the quantity. Enter the yard’s Price per BF to see your total estimated cost.
- Click Calculate: Instantly see your total Board Feet and total cost.
The Board Foot Formulas and Examples
Calculating board feet requires a slightly different formula depending on how you measured the length of your wood.
If your length is measured in FEET:
- Formula: (Thickness in inches × Width in inches × Length in feet) / 12
- Example: You have a board that is 2 inches thick, 6 inches wide, and 8 feet long.
- Math: (2 × 6 × 8) = 96. Divide by 12 = 8 BF.
If your length is measured in INCHES:
- Formula: (Thickness in inches × Width in inches × Length in inches) / 144
- Example: You have a board that is 1 inch thick, 5 inches wide, and 48 inches long.
- Math: (1 × 5 × 48) = 240. Divide by 144 = 1.67 BF.
The Hardwood Quarter Scale
When shopping for rough lumber, you will often see thickness listed as a fraction (like 4/4 or 8/4) instead of standard inches. This is called the quarter scale, and it indicates how many quarters of an inch thick the rough board is. Use this chart to know exactly what to type into the “Thickness” box on the calculator.
| Quarter Scale Size | Decimal Equivalent to Enter | Actual Rough Thickness |
| 4/4 (Four-Quarters) | 1.00 | 1 inch |
| 5/4 (Five-Quarters) | 1.25 | 1 ¼ inches |
| 6/4 (Six-Quarters) | 1.50 | 1 ½ inches |
| 8/4 (Eight-Quarters) | 2.00 | 2 inches |
| 10/4 (Ten-Quarters) | 2.50 | 2 ½ inches |
| 12/4 (Twelve-Quarters) | 3.00 | 3 inches |
Frequently Asked Questions (FAQs)
What is the difference between a linear foot and a board foot?
A linear foot only measures the length of the material, completely ignoring how thick or wide it is. A board foot is a measurement of total volume (length, width, and thickness combined).
Why is hardwood sold by the board foot?
Unlike standard construction pine (which is cut to uniform sizes like a 2×4), rough-sawn hardwoods are milled to maximize the yield from a tree. This means they come in completely random widths and lengths. Selling it by volume (board feet) ensures you only pay for the exact amount of wood you are getting.
Should I calculate board feet using nominal or actual dimensions?
You should always calculate using the nominal (rough) dimensions. Lumber yards sell the wood based on its size before it is planed, surfaced, and sanded smooth. Even if a 4/4 board actually measures 13/16″ thick after surfacing, you are still charged for the full 1-inch rough volume.
How do I calculate the cost of my lumber?
To find your total cost, simply multiply your total Board Feet by the supplier’s price per BF. For example, if you need 15 BF of Walnut, and the yard charges $9.00 per BF, your total cost will be $135.00. (Our calculator handles this step automatically!).
Does the shape of the wood matter?
No. Because a board foot is strictly a measurement of volume (144 cubic inches), it does not matter if the wood is wide and flat or perfectly square. A piece of wood measuring 1″ thick × 12″ wide × 12″ long has the exact same board foot volume as a piece measuring 2″ thick × 6″ wide × 12″ long.