How I Learned to Calculate Board Feet for My Woodworking Projects

When I decided to get into woodworking as a hobby, I was full of excitement to start my first project. But I quickly hit my first hurdle: buying lumber. At the lumberyard, I kept hearing the term "board foot," which sounded like an insider secret that left me, a beginner, completely stumped.

To avoid buying the wrong amount of wood, I was determined to figure it out. It turned out to be much simpler than I thought. This guide shares my learning process, and I hope it can help other woodworking newcomers like me.

Part 1: Unraveling the Mystery of the Formula

1. Finding the core formula. After some research, I found the most common formula. It cleverly combines feet and inches, which is what confused me at first.

Formula: Board Feet = [Length (ft) x Width (in) x Thickness (in)] / 12

I quickly understood the logic: the formula converts the width and thickness from inches to feet by dividing by 12, giving a calculation of the lumber's volume.

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2. Discovering the "all-inches" formula. Sometimes, I work with shorter pieces where it's easier to measure everything in inches. That's when this formula comes in handy.

Formula: Board Feet = [Length (in) x Width (in) x Thickness (in)] / 144

The key here is dividing by 144 (12 x 12), because both length and width need to be converted from inches to feet.



Part 2: My First Real Calculation

To truly master it, I grabbed a board I had on hand to practice.

1. Measure the thickness. I used a tape measure and found the board's "nominal thickness" was 2 inches. In woodworking, we typically use the rough-sawn nominal dimensions, not the finished, or "actual," dimensions.

2. Measure the width. Next, I measured its width, which was 4 inches.

3. Measure the length. Finally, I measured its length, which was 10 feet.

4. Plug it into the formula. I plugged these numbers into the first formula I learned:

Calculation: Board Feet = [10 ft x 4 in x 2 in] / 12

Multiply the top numbers: 80 / 12

The result: 6.67 Board Feet. I did it!



Part 3: My Time-Saving "Secret Weapon"

Calculating one board by hand felt like an accomplishment, but when my projects required multiple pieces of different sizes, standing in the store fumbling with my phone's calculator was a hassle. That's when I found a great online tool that helped me out.

For anyone who needs to calculate board feet quickly and accurately, I highly recommend this site: Board Foot Calculator.

You just enter the dimensions and quantity, and it gives you the result instantly. This was especially useful when I needed to compare the costs of different types of wood, saving me a ton of time and effort.

Important Tips I Learned

Nominal vs. Actual Dimensions: This is where beginners can easily make a mistake. Hardwood is sold by its "nominal" dimensions (like 8/4, meaning 2 inches thick). Even if it's planed down to an actual thickness of 1¾ inches, you still calculate the price based on the 2-inch nominal thickness.

Handling Fractions: If a dimension has a fraction, like 6½ inches, it's best to convert it to a decimal (6.5) to make the calculation easier.



I hope my learning experience helps you start your own woodworking journey. Understanding board feet is the first step toward becoming more proficient, and using the right tools can make that journey much smoother and more enjoyable.