Measuring rough cut lumber typically involves determining its dimensions—width, thickness, and length—to calculate its volume, most commonly expressed in board feet.
To measure rough cut lumber, you'll need a measuring tape. Unlike dressed lumber (which has consistent, planed dimensions), rough cut lumber's measurements can vary slightly along its length and width due to the milling process. When measuring rough cut lumber, it's generally best to measure the dimensions at a few points and use the smallest or average measurement, or whatever method is agreed upon for pricing.
Here are the key dimensions to measure:
- Thickness: Measure the thickness of the board in inches.
- Width: Measure the width of the board in inches.
- Length: Measure the length of the board in feet or inches.
Once you have these measurements, you can calculate the board feet using specific formulas.
Understanding Board Feet
A board foot is a unit of lumber volume equal to a piece of wood 1 inch thick, 12 inches wide, and 1 foot long. While the dimensions are nominal, the volume is equivalent to 144 cubic inches (1" x 12" x 12").
Calculating Board Feet Using Formulas
The provided references offer several standard formulas for calculating board feet:
Reference 1: Width (in) x Thickness (in) x Length (in) / 144 = Board Feet
- This formula requires all measurements to be in inches.
- Example: A board measuring 2 inches thick, 6 inches wide, and 8 feet long (which is 96 inches).
- Calculation:
6 inches x 2 inches x 96 inches / 144 = 1152 / 144 = 8 Board Feet
- Calculation:
Reference 2: Width (in) x Thickness (in) x Length (ft) / 12 = Board Feet
- This is a very common formula, using width and thickness in inches and length in feet. The division by 12 converts the (inch x inch x foot) measurement into board feet (which is based on a 12-inch width).
- Example: The same board measuring 2 inches thick, 6 inches wide, and 8 feet long.
- Calculation:
6 inches x 2 inches x 8 feet / 12 = 96 / 12 = 8 Board Feet
- Calculation:
Reference 3: Pieces x Width (in) x Thickness (in) x Length (ft) / 12 = Board Feet
- This formula is useful for calculating the total board footage of multiple pieces of lumber with the same dimensions.
- Example: Calculating the total board feet for 5 boards, each measuring 2 inches thick, 6 inches wide, and 8 feet long.
- Calculation:
5 pieces x 6 inches x 2 inches x 8 feet / 12 = 5 x 96 / 12 = 5 x 8 = 40 Board Feet
- Calculation:
Summary of Board Foot Formulas
Here's a quick reference for the formulas:
| Formula Number | Description | Formula | Notes |
|---|---|---|---|
| 1 | All dimensions in inches | W(in) x T(in) x L(in) / 144 = BF |
Useful if length is easily measured in inches |
| 2 | Width & Thickness in inches, Length in feet | W(in) x T(in) x L(ft) / 12 = BF |
Most commonly used formula |
| 3 | Multiple pieces of the same size | Pieces x W(in) x T(in) x L(ft) / 12 = Total BF |
For calculating total of a bundle/pile |
Practical Tips for Measuring Rough Lumber
- Measure Carefully: Rough lumber dimensions can vary. Be consistent in where you measure (e.g., middle of the board, or the narrowest/thinnest point).
- Round Down: When selling, it's common practice to round down fractions of an inch or foot to the nearest whole or half unit to be conservative.
- Understand Nominal vs. Actual: While rough lumber is closer to nominal size than dressed lumber, it's still sold based on its actual rough dimensions measured before drying and surfacing.
- Use a Calculator: Especially when dealing with many pieces or complex calculations, using a calculator or spreadsheet can prevent errors.
By accurately measuring the width, thickness, and length of rough cut boards and applying the appropriate formula, you can correctly determine the board footage.
