CALCWOVEN • LUMBER
Board Foot Calculator
Calculate board feet for lumber from thickness, width, length and quantity. Add a waste allowance and price per board foot for an instant material-cost estimate.
Enter valid positive dimensions and a whole-number quantity to calculate results.
Lumber dimensions
Use the dimensions your supplier uses for board-foot billing.
Cost (optional)
Estimated lumber
- Board feet per board5.33 bd ft
- Before waste5.33 bd ft
- Waste allowance0.53 bd ft (10%)
- Total board feet5.87 bd ft
- Estimated cost—
Board-foot calculations measure volume, not finished surface area.
Formula: thickness × width × length ÷ 12 × quantity. Then 10% waste is added.
HOW IT WORKS
How to calculate board feet
A board foot is a lumber-volume unit equal to a piece 1 inch thick, 12 inches wide and 12 inches long. When thickness and width are in inches and length is in feet, use: board feet = thickness × width × length ÷ 12. Multiply by quantity for several identical boards. For a step-by-step measuring guide covering rough vs surfaced lumber, random widths and nominal vs actual sizes, read how to measure board feet.
Example: how many board feet are in a 2×4×8?
Using nominal dimensions, 2 × 4 × 8 ÷ 12 = 5.33 board feet. If your supplier prices surfaced lumber using a different billed thickness or width, enter the dimensions used for that supplier’s board-foot calculation.
What do 4/4, 5/4, 6/4 and 8/4 mean?
Hardwood thickness is often written in quarters. 4/4 means 1 inch, 5/4 means 1.25 inches, 6/4 means 1.5 inches and 8/4 means 2 inches before surfacing. The calculator includes these as quick presets.
QUICK ANSWERS
Board foot calculator FAQ
What is the difference between a board foot and a linear foot?
A linear foot measures length only. A board foot measures lumber volume, so thickness and width matter as well as length.
What is the difference between a board foot and a square foot?
A square foot measures surface area. A board foot includes thickness, so two pieces with the same face area can contain different board-foot volumes.
Should I add waste when buying lumber?
Often yes. Defects, grain selection, trimming and project cuts can increase the amount you need. Use the waste setting as a planning allowance rather than a fixed rule.
Can I calculate lumber cost?
Yes. Enter your supplier’s price per board foot and the calculator multiplies it by the total board feet including the selected waste allowance.
MORE TOOLS
Planning a deck or other lumber project?
Use the Deck Footing Calculator for foundation material planning, or browse All Calculators for more project tools.
This calculator estimates board-foot volume from the dimensions you enter. Lumber grading, surfacing, rounding and billing practices can vary by supplier.