A board foot is 144 cubic inches of lumber: thickness times width times length in inches, divided by 144. A piece 1 inch thick, 6 inches wide and 96 inches long is 1 times 6 times 96, over 144, which is 4 board feet. Enter your dimensions and quantity to get the total board feet.
Calculations run in your browser. Inputs are not sent to our servers; anything you Save stays in this browser only.
Saved results (0)
How to Use the Board Foot Calculator
- Enter the board thickness in inches, using the rough stock size.
- Enter the width in inches.
- Enter the length in inches, remembering 8 feet is 96 inches.
- Enter the quantity, then read the total board feet.
| Result | What it means |
|---|---|
| Total board feet | The lumber measure for all your boards together. |
| Board feet per piece | The board feet in a single board. |
| Cubic feet | The same volume in cubic feet. |
| Cubic metres | The volume in metric units. |
What Is a Board Foot?
A board foot is the standard way rough hardwood lumber is measured and sold in North America. One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long, or any shape with the same volume of 144 cubic inches.
Because lumber is priced per board foot, working out the board feet of a project is the key to buying the right amount and knowing the cost. It matters most for thick, wide hardwood boards, where the figure is far from obvious. A quick glance at a stack of rough boards tells you almost nothing about the volume of wood in front of you, which is exactly why the board foot exists as a fair unit for buyer and seller alike.
How Does the Board Foot Calculation Work?
board feet = thickness x width x length (in) / 144- Multiply thickness by width by length, all in inches.
- Divide by 144, the number of cubic inches in a board foot.
- Multiply by the quantity of identical boards.
- Divide board feet by 12 for cubic feet if you need volume.
Use the rough or nominal thickness that the lumber is sold at, since board feet are measured before the wood is planed to its final size. This is why a board that measures a hair under an inch once dressed is still charged as full 4/4 stock: you are paying for the rough board the mill cut, not the thinner piece you take home after planing.
Board Foot Example
You have a board 1 inch thick, 6 inches wide and 96 inches long. Multiplying gives 576 cubic inches, and dividing by 144 gives 4 board feet. Ten of them would be 40 board feet. A thicker 8/4 board, 2 inches thick, of the same width and length would be double, at 8 board feet each, showing how thickness drives the figure. Getting into the habit of running every board through the formula before you buy is the single easiest way to avoid the two classic hardwood mistakes, coming home short of wood or paying for far more than the project ever needed.
What Affects Board Feet
Thickness
Board feet scale directly with thickness, so 8/4 stock is twice the board feet of 4/4 at the same size.
Width and Length
Both raise the board feet in proportion; a wider or longer board costs more lumber.
Rough vs Finished Size
Lumber is measured rough, before planing, so use the nominal thickness the mill quotes.
Quantity
Multiply by the number of boards; a project total is the sum of every piece.
Board Feet Compared by Board Size
Board feet for some standard sizes at 8 feet long.
| Nominal size | Length | Board feet |
|---|---|---|
| 1 x 4 | 8 ft | 2.67 |
| 1 x 6 | 8 ft | 4.00 |
| 2 x 4 | 8 ft | 5.33 |
| 2 x 8 | 8 ft | 10.67 |
These use nominal sizes; actual planed dimensions are smaller, but lumber is sold by the nominal measure.
When to Use a Board Foot Calculator
Buying Hardwood
Work out the board feet to price a purchase at the lumberyard.
Estimating a Project
Add up the board feet of every part to know how much to buy.
Comparing Boards
See how thickness and size change the lumber in a board.
Common Board Foot Mistakes
1. Mixing Feet and Inches
The 144 formula needs all three dimensions in inches; convert feet first.
2. Using Planed Thickness
Board feet are measured rough, so use the nominal thickness, not the finished size.
3. Forgetting Quantity
A single board foot figure is per board; multiply by how many you need.
4. Ignoring Waste
Board feet cover the boards themselves; add extra for offcuts and defects.
Accuracy and Limitations
The board-foot maths is exact for the dimensions you enter. It measures lumber volume, not the finished yield after milling.
What it calculates accurately
- Board feet per piece and in total
- Volume in cubic feet and metres
- Any thickness, width and length
What it does not do
- Add a waste allowance for offcuts
- Convert to a price without a rate
- Account for planing losses
How We Calculate the Result
Frequently Asked Questions
How do you calculate board feet?
Multiply thickness by width by length in inches and divide by 144. A 1 by 6 by 96 inch board is 4 board feet.
What is a board foot?
A board foot is 144 cubic inches of lumber, such as a piece 1 inch thick, 12 inches wide and 12 inches long.
How many board feet in a 2x4x8?
A nominal 2 by 4 that is 8 feet long is 5.33 board feet: 2 times 4 times 96, divided by 144.
Do I use rough or finished size?
Use the nominal, rough size the lumber is sold at, since board feet are measured before the wood is planed.
How do I turn board feet into cost?
Multiply the board feet by the price per board foot. Our lumber cost calculator does this and adds a waste allowance.
How many board feet in a cubic foot?
There are 12 board feet in a cubic foot, since a board foot is one twelfth of a cubic foot.
Does board foot apply to plywood?
No. Sheet goods like plywood are sold by the sheet or square foot, not the board foot. Use our plywood calculator instead.
Should I add waste?
Yes. Board feet cover the boards; add 10 to 20 percent for offcuts, defects and mistakes when buying.
Is my data saved?
No. The calculator runs entirely in your browser and nothing you enter is stored or sent anywhere.
Sources
- Board foot (Wikipedia).
- Lumber (Wikipedia).
- Units of volume (Wikipedia).
Related Calculators
Buying lumber?
Explore all hobby calculatorsFor woodworking estimation and educational use. Board feet use nominal rough dimensions; add a waste allowance for offcuts and defects when ordering. Spotted an error? Let us know.
Author
Shakeel Muzaffar is the Founder and Editor-in-Chief of MultiCalculators.com, bringing over 15 years of experience in digital publishing, product strategy, and online tool development. He leads the platform's editorial vision, ensuring every calculator meets strict standards for accuracy, usability, and real-world value. Shakeel personally oversees content quality, formula verification workflows, and the platform's commitment to publishing tools that are genuinely useful for students, professionals, and everyday users worldwide.
