Board Feet Calculator
Calculate lumber board feet from thickness, width, length, and quantity.
Plan your lumber purchase
Calculate board feet, total volume, waste, weight and cost instantly.
1. Choose how your lumber is measured
2. Enter board dimensions
Nominal sizes are converted to common dressed-lumber dimensions.
3. Add waste and pricing
10% is a useful starting point for cuts and defects.
Adjust any measurement to update the purchase estimate.
How to calculate board feet
A board foot is the standard unit for pricing and measuring rough lumber — equal to a piece of wood 1 inch thick, 12 inches wide, and 12 inches long. This calculator converts a board's actual dimensions and quantity into total board feet, the figure lumber yards use for pricing.
How the calculation works
Board feet = (Thickness × Width × Length × Quantity) ÷ 12, where thickness and width are in inches and length is in feet. Dividing by 12 converts the raw cubic-inch-per-foot figure into the standard board-foot unit.
Example
10 boards, each 2 inches thick, 6 inches wide, and 8 feet long: Board feet = (2 × 6 × 8 × 10) ÷ 12 = 960 ÷ 12 = 80 board feet.
Frequently asked questions
What's the difference between board feet and linear feet?
Linear feet measures only length, ignoring width and thickness — useful for uniform trim or molding. Board feet accounts for all three dimensions and is the standard unit for pricing dimensional and rough lumber, where board thickness and width vary.
Why does lumber use nominal sizing instead of actual dimensions?
Nominal sizing (like '2x4') refers to the lumber's dimensions before it's dried and surfaced (planed smooth), which reduces the actual size. The trade has kept nominal sizing as the standard naming and pricing convention even though the finished board is smaller.
Board Feet Calculator
Board feet = (Thickness × Width × Length × Quantity) ÷ 12, where thickness and width are in inches and length is in feet. Dividing by 12 converts the raw cubic-inch-per-foot figure into the standard board-foot unit.
Let's understand your board feet result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Board Feet
- Board footage is based on nominal (stated) lumber dimensions, not actual finished dimensions — a nominal 2x6 is actually closer to 1.5 x 5.5 inches once surfaced, but lumber is priced and measured by its nominal size.
- This calculation is for rough-sawn or nominal lumber pricing; for finished/surfaced lumber projects where exact dimensions matter for fit, use the actual (not nominal) measurements separately for your cut list.
- Board feet only accounts for volume, not waste from knots, warping, or defects — factor in extra material for grading and defect allowance separately when ordering.
Common Board Feet Mistakes to Avoid
- Using actual (surfaced) dimensions instead of nominal dimensions when the lumber yard prices by nominal size — this will produce a board-foot count that doesn't match what you're actually being charged for.
- Forgetting that length must be in feet while thickness and width are in inches — mixing units here is the most common board-foot calculation error.
When to Use This Calculator
A board foot is the standard unit for pricing and measuring rough lumber — equal to a piece of wood 1 inch thick, 12 inches wide, and 12 inches long. This calculator converts a board's actual dimensions and quantity into total board feet, the figure lumber yards use for pricing.