Board Foot Calculator
Whether you’re building a custom bookshelf, framing a house, or planning a woodworking project, knowing exactly how much lumber you need saves both money and frustration. A board foot is the standard unit of measure for lumber in North America, representing a volume of 144 cubic inches equivalent to a board that’s 1 inch thick, 12 inches wide, and 12 inches long. This board foot calculator helps you determine the total lumber volume required for any project, accounting for dimensions, quantity, and even a waste factor for cuts and mistakes.
Carpenters, contractors, DIY enthusiasts, and furniture makers all rely on accurate board foot calculations to estimate material costs and avoid costly overages or shortages. The calculator handles multiple units inches, feet, millimeters, centimeters, meters, and yards so you can work with whatever measurements you have on hand.
Techraxy built this board foot calculator to simplify lumber estimation. Everything runs locally in your browser, so your project data stays private while you plan your next build.
How to Use the Board Foot Calculator
Enter the thickness, width, and length of your lumber in your preferred units.
Set the number of pieces you need for your project.
Enter the price per board foot and choose your currency from the dropdown menu.
Adjust the waste factor percentage to account for cuts, defects, and mistakes.
Click Calculate or simply change any input — the results update automatically.
Review the summary tab for total board feet and estimated cost, or switch to the detailed breakdown tab for a complete itemized view.
How the Board Foot Formula Works
The board foot is a standardized unit of lumber volume that simplifies buying and selling rough-sawn and surfaced lumber. The calculator determines board feet using the standard industry formula:
Board Feet = (Thickness in inches × Width in inches × Length in feet) / 12
This formula works because a board foot represents 144 cubic inches of wood. When lumber is sold by the board foot, the price is set per unit volume regardless of the specific dimensions.
The calculator automatically converts your input units to inches for thickness and width, and to feet for length, before applying the formula. This ensures accurate results whether you’re working in metric or imperial units.
With Quantity: Total Board Feet = Board Feet per Piece × Number of Pieces
With Waste Factor: Total with Waste = Total Board Feet × (1 + Waste Percentage / 100)
Cost Calculation: Estimated Cost = Total Board Feet × Price per Board Foot
The waste factor accounts for lumber that becomes unusable due to cutting, defects, warping, or mistakes — a practical consideration for any real-world project.
Worked Example
A woodworker is building a farmhouse dining table and needs to estimate lumber costs. The table top requires five boards, each measuring 1.5 inches thick, 8 inches wide, and 6 feet long.
Step 1: Identify the inputs — Thickness = 1.5 in, Width = 8 in, Length = 6 ft, Quantity = 5 pieces.
Step 2: Calculate board feet per piece — (1.5 × 8 × 6) / 12 = 72 / 12 = 6 BF per board.
Step 3: Multiply by quantity — 6 × 5 = 30 total board feet.
Step 4: Apply a 15% waste factor — 30 × 1.15 = 34.5 BF with waste.
Step 5: Calculate cost at $4.50 per board foot — 30 × 4.50 = $135 total, or $155.25 with waste included.
The woodworker needs about 30 board feet of lumber for the table, or 34.5 board feet when accounting for waste. This estimate helps with budgeting and ensures enough material is purchased for the project.
