Estimating Practice Exam

What is the correct method to calculate the board measure (BM) of lumber?

1. Multiply length in feet by width and thickness in inches, then divide by 12

2. Multiply length in inches by height in feet, then divide by 100

3. Add the nominal width to the thickness, then multiply by length in feet

4. Multiply the weight of the lumber by its length in inches

The correct answer is: Multiply length in feet by width and thickness in inches, then divide by 12

The method to calculate board measure (BM) of lumber is to multiply the length in feet by the width and thickness in inches, and then divide by 12. This calculation is essential because the board measure is expressed in terms of board feet, which is a volume measurement commonly used in the lumber industry. To break it down: 1. **Length in Feet**: Since board measure is ultimately expressed in a foot-based measurement, using length in feet allows for a straightforward calculation. 2. **Width and Thickness in Inches**: The width and thickness must be expressed in inches because they provide the cross-sectional area of the lumber in square inches. This is crucial for determining the volume. 3. **Division by 12**: This step converts cubic inches to board feet, as one board foot is equivalent to 144 cubic inches (1 foot x 1 foot x 1 inch = 144 cubic inches). The division by 12 accounts for the fact that you are measuring volume (which is based on three dimensions) in a way that aligns with the board foot measurement. Therefore, this formula effectively converts the dimensions of the lumber into a standard volume measurement useful for estimating purposes.