Calculate board feet, volume, and cost for lumber projects. Free lumber calculator with waste factor, delivery costs, and detailed breakdown.
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Every woodworking project starts with a trip to the lumber yard but figuring out exactly how much lumber to buy can be surprisingly complicated. Between nominal sizes and actual sizes, board feet calculations, and the ever-present question of how much waste to account for, it’s easy to end up with either too little material or a pile of expensive leftovers. Getting the estimate right from the start saves money, reduces waste, and keeps your project moving without frustrating trips back to the store.
This lumber calculator handles the math for you, converting your dimensions into board feet, the standard unit for buying and selling lumber and providing a complete cost breakdown. Whether you’re a professional contractor estimating materials for a framing job, a woodworker planning a furniture project, or a DIY enthusiast building a deck or shed, this tool delivers instant, accurate estimates. Enter the dimensions, quantity, price per board foot, waste factor, and delivery costs, the calculator does the rest. All processing runs locally in your browser, keeping your data private.
Enter the length of each lumber piece using the first input field, selecting from feet, inches, meters, centimeters, or millimeters.
Specify the width of each piece, be sure to use the actual width, not the nominal size (e.g., a 2×6 is actually 5.5 inches wide).
Enter the thickness of each piece using the actual thickness (a 2×4 is actually 1.5 inches thick).
Enter the quantity of pieces you need for your project.
Set the price per board foot, this is the cost you’ll pay at the lumber yard or supplier.
Adjust the waste factor to account for cuts, defects, and mistakes 10% is typical for most projects.
Add any delivery or miscellaneous costs to get a complete project estimate.
Review the summary or switch to the detailed breakdown tab for a full component list.
The calculator determines the board footage and volume of lumber based on the dimensions and quantity. Board feet is the standard unit used in the lumber industry for pricing and estimating.
Formula: Board Feet = (Thickness × Width × Length) / 144
All dimensions must be in inches. One board foot equals 144 cubic inches (12 inches × 12 inches × 1 inch). For example, a 1×6×8 board (1 inch thick, 6 inches wide, 8 feet long) has: (1 × 6 × 96) / 144 = 4 board feet.
Formula: Volume (cubic feet) = Length (ft) × Width (ft) × Thickness (ft) × Quantity
For volume in cubic feet, all dimensions are converted to feet. This is useful for shipping and handling calculations.
Formula: Total Cost = Total Board Feet × Price per Board Foot
The cost is based on board feet — the standard pricing unit for lumber. The calculator also applies a waste factor and adds delivery or miscellaneous costs.
Formula: Total with Waste = Total Board Feet × (1 + Waste Factor / 100)
The waste factor accounts for cuts, defects, mistakes, and other losses. A 10% waste factor is common for most projects.
Consider a project requiring 10 pieces of 2×6 lumber, each 8 feet long. The price per board foot is $2.50, with a 10% waste factor and no delivery costs.
Step 1: Convert dimensions to inches
Thickness: 2 in (actual thickness is 1.5 in for a 2×6, but in lumber pricing, nominal dimensions are used for calculation)
Width: 6 in
Length: 8 ft × 12 = 96 in
Step 2: Calculate board feet per piece
BF = (2 × 6 × 96) / 144 = 1,152 / 144 = 8 BF per piece
Step 3: Calculate total board feet
Total BF = 8 × 10 = 80 BF
Step 4: Apply waste factor and cost
Total BF with waste = 80 × 1.10 = 88 BF
Cost = 88 × $2.50 = $220.00
Interpretation: A project requiring 10 pieces of 2×6×8 lumber needs 80 board feet of lumber, but with a 10% waste factor, you should budget for 88 board feet. The total cost is $220. This estimate helps you plan your purchase and avoid running short during the build.
Board feet measure volume (length × width × thickness in inches, divided by 144), while linear feet measure length only. For example, a 2×4×8 board is 8 linear feet but 5.33 board feet. Lumber is priced by board foot, not linear foot, because it accounts for the thickness and width of the material.
To convert square feet to board feet, multiply the area (in square feet) by the thickness (in inches). For example, 100 square feet of 1-inch thick lumber is 100 board feet. 100 square feet of 2-inch thick lumber is 200 board feet. This works because 1 square foot × 1 inch thick = 1 board foot.
A typical waste factor for lumber is 10–15%. This accounts for cuts, defects, mistakes, and pieces that are too short to use. Complex projects with many angled cuts or intricate joinery may require a 15–20% waste factor. Simple projects with straight cuts can sometimes use a 5–10% waste factor.
Lumber costs vary widely by species, grade, and region. Construction lumber (SPF) typically costs $1.50–$4.00 per board foot. Hardwoods range from $2.50–$8.00 per board foot. Premium species like walnut, cherry, or mahogany can cost $10–$20 per board foot or more. Always check current prices at your local supplier.
One board foot equals 144 cubic inches. Since 1 cubic foot equals 1,728 cubic inches, one board foot equals 144/1728 = 1/12 cubic foot, or approximately 0.0833 cubic feet. This is why 12 board feet equals 1 cubic foot.
Nominal sizes refer to the dimensions of the lumber before it’s planed and dried. A 2×4 is actually 1.5×3.5 inches after planing and drying. The board foot calculation uses nominal dimensions for pricing purposes, but when you’re working with the lumber, you need to account for the actual dimensions.
For irregular shapes, it’s best to break the piece down into rectangular sections and calculate each section separately. For round or curved pieces, you may need to estimate the volume by approximating the shape with rectangles or using more advanced methods. The calculator is designed for rectangular lumber.
Rough sawn lumber has not been planed and retains its nominal dimensions more closely. Surfaced lumber (S4S: surfaced four sides) has been planed to a consistent size, reducing the actual dimensions. Board foot calculations typically use nominal dimensions for both, but the actual volume of surfaced lumber is slightly less than the board foot calculation suggests.
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