Lumber Calculator
Calculate board feet and estimate lumber costs for your woodworking or construction project. Enter your lumber dimensions and quantity to get accurate board feet calculations, total linear feet, and cost estimates based on your price per board foot.
How to Use This Lumber Calculator
- Choose between custom dimensions or standard lumber sizes using the toggle buttons
- For custom sizes: enter thickness (inches), width (inches), and length (feet) based on your specific lumber
- For standard sizes: select from common dimensional lumber like 2x4, 2x6, 4x4, etc. The calculator automatically uses actual dimensions
- Enter the quantity of pieces you need for your project
- Optionally enter a price per board foot for accurate cost estimation
- View total board feet, board feet per piece, linear feet, and estimated costs
Note: Standard lumber sizes use actual dimensions, not nominal. A "2x4" actually measures 1.5" x 3.5" after kiln drying and planing. This calculator automatically accounts for actual dimensions when using standard sizes.
What is a Board Foot?
A board foot is the standard unit of measurement for lumber volume used throughout North America. One board foot equals a piece of wood that is one inch thick, twelve inches wide, and twelve inches long (1" x 12" x 12"), totaling 144 cubic inches of wood. This standardized measurement allows lumber of various dimensions to be compared and priced consistently across different suppliers and wood species.
Lumber mills and hardwood dealers almost always price wood by the board foot rather than by the piece. This makes the board foot calculation essential for estimating project costs accurately. Understanding board feet helps woodworkers and contractors compare prices between different suppliers, evaluate costs across wood species, budget for projects precisely, and minimize waste by ordering exactly the right amount of material.
For construction lumber (like framing studs), wood is typically sold by the linear foot or piece. However, for hardwoods, specialty woods, and mill-direct purchases, board feet is the universal pricing standard.
Nominal vs. Actual Lumber Dimensions
Understanding the difference between nominal and actual dimensions is critical for accurate calculations:
- Nominal size: The name used to describe lumber (e.g., 2x4, 1x6). This reflects the rough-cut size before processing
- Actual size: The real dimensions after kiln drying and surfacing (planing). A 2x4 actually measures 1.5" x 3.5"
Common dimensional lumber conversions:
- 1x boards: Actually 0.75" thick (3/4 inch)
- 2x boards: Actually 1.5" thick
- 4x boards: Actually 3.5" thick
- Width reduction: Actual width is typically 0.5" less than nominal for boards up to 6" wide, and 0.75" less for wider boards
Board Feet Formulas
The formula for calculating board feet depends on your length measurement:
When all dimensions are in inches:
Board Feet = (Thickness x Width x Length) / 144
When length is in feet (most common):
Board Feet = (Thickness x Width x Length) / 12
Where thickness and width are in inches, and length is in feet.
Common Board Foot Reference Values
Board foot values for standard 8-foot boards:
- 1x4 (8ft): 2.67 board feet
- 1x6 (8ft): 4 board feet
- 1x8 (8ft): 5.33 board feet
- 2x4 (8ft): 5.33 board feet
- 2x6 (8ft): 8 board feet
- 2x8 (8ft): 10.67 board feet
- 2x10 (8ft): 13.33 board feet
- 2x12 (8ft): 16 board feet
- 4x4 (8ft): 10.67 board feet
Lumber Pricing Tips
- Hardwood prices typically range from $3-15 per board foot depending on species and grade
- Exotic woods can cost $15-50 or more per board foot
- Buying rough-sawn lumber saves money but requires additional surfacing
- Lumber prices fluctuate seasonally and with market conditions
- Buying in larger quantities often provides volume discounts at lumber yards
- Always add 15-20% extra for waste, defects, and cutting errors