Board Feet Calculations For Finding Overall Feet

Welcome to our free Board Feet Calculator! Quickly determine the board footage of your lumber based on its dimensions and the number of pieces. Our Board Feet Calculation tool helps you estimate material needs for your projects.

Calculate Board Feet

What is Board Feet Calculation?

A Board Feet Calculation is a method used to determine the volume of lumber. One board foot (BDFT or FBM – foot, board measure) is the volume of a piece of wood that is one foot long, one foot wide, and one inch thick (1 ft x 1 ft x 1 in, or 12 in x 12 in x 1 in = 144 cubic inches). The Board Feet Calculator simplifies this process, especially when dealing with multiple pieces or non-standard dimensions. Understanding board feet is crucial for anyone involved in woodworking, construction, or lumber sales, as lumber is often priced and sold by the board foot.

Anyone buying, selling, or working with rough-sawn or finished lumber should use a Board Feet Calculation. This includes carpenters, furniture makers, contractors, lumber yards, and DIY enthusiasts. It ensures accurate material estimation and costing for projects. The Board Feet Calculator above helps make these calculations quick and error-free.

A common misconception is that board feet directly relate to the linear feet of a board, regardless of its thickness and width. However, board feet is a measure of volume, so a 2×6 eight feet long will have more board feet than a 1×6 eight feet long. Our Board Feet Calculator takes all three dimensions into account.

Board Feet Formula and Mathematical Explanation

The standard formula for calculating board feet is:

Board Feet (BDFT) = (Thickness (inches) × Width (inches) × Length (feet)) / 12

Alternatively, if the length is also measured in inches:

Board Feet (BDFT) = (Thickness (inches) × Width (inches) × Length (inches)) / 144

The division by 12 (or 144) is necessary to convert the volume from units based purely on inches (and feet for length in the first formula) into the standard board foot unit, which is equivalent to 144 cubic inches.

To find the total board feet for multiple identical pieces, you multiply the board feet of one piece by the number of pieces:

Total Board Feet = BDFT per piece × Number of Pieces

Our Board Feet Calculator uses these formulas for accurate results.

Variables Table

Table: Variables used in Board Feet Calculation.

Variable	Meaning	Unit	Typical Range
Thickness (T)	The thickness of the lumber	inches	0.25 – 12
Width (W)	The width of the lumber	inches	1.5 – 24
Length (L)	The length of the lumber	feet	1 – 24
Number of Pieces (N)	Quantity of identical lumber pieces	–	1 – 1000+
Board Feet (BDFT)	Volume of lumber	Board Feet	0.1 – 1000+

Practical Examples (Real-World Use Cases)

Example 1: Decking Project

You are building a deck and need to buy 50 pieces of 2×6 lumber, each 12 feet long. Assuming “2×6” actually measures 1.5 inches thick and 5.5 inches wide:

• Thickness = 1.5 inches
• Width = 5.5 inches
• Length = 12 feet
• Number of Pieces = 50

Using the Board Feet Calculation: BDFT per piece = (1.5 * 5.5 * 12) / 12 = 8.25 BDFT.

Total BDFT = 8.25 * 50 = 412.5 BDFT. You would need to purchase 412.5 board feet of lumber. Our Board Feet Calculator gives this result instantly.

Example 2: Bookshelf Material

You are making a bookshelf and require 5 boards of 1×10 lumber, each 6 feet long. “1×10” is actually 0.75 inches by 9.25 inches:

• Thickness = 0.75 inches
• Width = 9.25 inches
• Length = 6 feet
• Number of Pieces = 5

Board Feet Calculation: BDFT per piece = (0.75 * 9.25 * 6) / 12 = 3.46875 BDFT.

Total BDFT = 3.46875 * 5 = 17.34 BDFT (approximately). You’d need around 17.34 board feet. Check out our Project Material Estimator for more detailed project planning.

How to Use This Board Feet Calculator

1. Enter Thickness: Input the thickness of your lumber in inches. Be sure to use the actual thickness if it differs from the nominal dimension (e.g., 1.5 for a 2x board).
2. Enter Width: Input the width of your lumber in inches, again using the actual dimension (e.g., 5.5 for a 2×6).
3. Enter Length: Input the length of one piece of lumber in feet.
4. Enter Number of Pieces: Input how many identical pieces of lumber you have or need.
5. Calculate: The Board Feet Calculator will automatically update the results as you type, or you can click “Calculate”.
6. Review Results: The calculator will show the board feet per piece, the total board feet for all pieces, and the total volume in cubic inches and feet.
7. Use Reset/Copy: Use “Reset” to clear and set default values, and “Copy Results” to copy the output.

The results from the Board Feet Calculator help you understand the total volume of lumber you’re dealing with, essential for purchasing and cost estimation. You might also find our Cost of Lumber tool useful.

Key Factors That Affect Board Feet Calculation Results

• Actual vs. Nominal Dimensions: Lumber is often sold by nominal dimensions (e.g., 2×4), but the actual dimensions after milling are smaller (e.g., 1.5″ x 3.5″). Using actual dimensions in the Board Feet Calculation gives a more accurate volume.
• Lumber Length: Longer boards will naturally have more board feet, assuming thickness and width are constant.
• Lumber Width: Wider boards contribute more to the board foot volume.
• Lumber Thickness: Thicker boards significantly increase the board feet.
• Number of Pieces: The total board feet scales directly with the number of pieces.
• Waste Factor: When purchasing lumber for a project, always account for waste due to cuts, knots, and defects. The Board Feet Calculator gives you the net volume; you should add a percentage for waste (often 10-15%). Our Lumber Waste Calculator can help estimate this.
• Milling Process: Rough-sawn lumber is closer to nominal dimensions than surfaced (S4S) lumber. Be aware of what you are measuring for the Board Feet Calculation.

Frequently Asked Questions (FAQ)

What is a board foot?

A board foot is a unit of volume for lumber equal to 144 cubic inches (12″ x 12″ x 1″). Our Board Feet Calculator measures this.

How do I calculate board feet for lumber with dimensions in inches only?

If length is in inches, use the formula: (Thickness (in) * Width (in) * Length (in)) / 144. Our Board Feet Calculator uses length in feet for convenience.

Why are actual lumber dimensions smaller than nominal?

Nominal dimensions refer to the size of the rough green lumber before drying and surfacing. The drying and milling processes reduce the final size.

Does the Board Feet Calculator account for wood type?

No, the Board Feet Calculation is purely a volume measurement and does not depend on the type of wood or its density. For density info, see our Wood Density Chart.

How do I calculate board feet for hardwood?

The formula is the same. Hardwoods are often sold by the board foot, and thicknesses are typically given in quarters of an inch (e.g., 4/4 = 1 inch, 8/4 = 2 inches thick).

What if my lumber pieces are of different sizes?

You need to perform a separate Board Feet Calculation for each group of differently sized pieces and then sum the results. Our Board Feet Calculator is designed for identical pieces per calculation.

How is board feet different from linear feet?

Linear feet is just a measure of length, while board feet is a measure of volume, considering thickness and width as well.

Do I need to include the kerf (saw cut width) in my calculations?

Not for the initial board foot volume of the purchased lumber. However, when planning cuts, you’ll lose material to the kerf, which contributes to waste.