Board Foot / Lumber Calculator
Convert lumber dimensions to board feet for buying and selling hardwood and softwood.
Reviewed by the ToolNestr Editorial Team — July 2026
How the board foot calculator works
The board foot calculator converts lumber dimensions into board feet — the standard unit for buying hardwood lumber. It uses the formula: board feet = (thickness in inches x width in inches x length in feet) / 12. The result represents the volume of wood in board foot units.
To use the calculator, enter the actual thickness and width of the lumber in inches and the length in feet. Select a common size preset to quickly fill in standard dimensions. The calculator also shows the actual size (which may differ from nominal), cubic inches, and an estimated total price based on a per-board-foot rate.
Board measurement conventions follow the National Hardwood Lumber Association (NHLA) grading rules used throughout the North American hardwood trade.
Measure the board
Measure thickness and width in inches, length in feet. Use actual not nominal dimensions.
Use presets or enter custom
Click standard lumber sizes or enter custom dimensions for a precise calculation.
Calculate cost
Enter the price per board foot to get the total cost of your lumber purchase.
The formula explained
Board foot formula
BF = (T × W × L) / 12. For a 2x4 that is actually 1.5″ x 3.5″ and 8 ft long: (1.5 × 3.5 × 8) / 12 = 3.5 board feet.
Total for multiple boards
Multiply the board feet per board by the number of identical boards. For 10 boards at 3.5 BF each: 10 × 3.5 = 35 board feet.
Cost calculation
Cost = BF × price per BF. At $3.50/BF: 3.5 × $3.50 = $12.25 per board.
Worked example
Buying 12 boards of 1x6 oak, each 6 ft long. Actual size is 0.75 x 5.5 inches. Price is $4.25 per board foot.
Use cases for the board foot calculator
Woodworking
Furniture makers calculate board feet for each project to estimate material costs. A dining table might need 40-60 BF of hardwood. The calculator helps you budget before visiting the lumber yard.
Framing lumber
Contractors estimate framing lumber in board feet for bidding. A typical 2,000 sq ft house might use 8,000-12,000 BF of dimensional lumber. The calculator handles any size, from 2x4 to 6x6.
Sawmill and timber
Sawmills sell rough-cut lumber by the board foot. The calculator converts log scale estimates into board feet. Use the Doyle or International rule to estimate board foot yield from standing timber.
Shipping and freight
Lumber freight rates are often based on board feet or thousand board feet (MBF). Calculate the total BF for an order to compare shipping quotes and estimate freight costs accurately.
Tips for buying lumber by the board foot
Understand nominal vs. actual
Softwood lumber (pine, fir, spruce) at home centers is sold by nominal dimensions and linear feet, not board feet. Hardwood lumber at specialty yards is sold by board foot using actual dimensions. Always confirm which measurement the seller uses before comparing prices.
Check for defects
When buying rough lumber, inspect for knots, checks, splits, and warp. These defects reduce the usable board footage. Factor in 10-20% waste for defects when calculating how much lumber to buy for a project.
Buy S2S for a consistent thickness
Surfaced two sides (S2S) lumber has planed faces for consistent thickness. Rough lumber varies in thickness and needs to be planed. When calculating board feet for S2S, use the surfaced dimensions (e.g., 13/16 inch instead of 4/4 rough).
Real-world context
A furniture maker building a walnut tabletop is a classic board-foot scenario. Six boards of 8/4 stock (actually 1.75 inches thick after milling), 7 inches wide and 8 feet long, each come to (1.75 × 7 × 8) / 12 = 8.17 board feet, for a total of about 49 board feet across the six boards — a number the woodworker uses to price the walnut before committing to the design, since 8/4 walnut can run well over $10 per board foot at specialty hardwood dealers.
Framing contractors work at a very different scale. A small shed built with 48 pieces of 2x6 (actual 1.5 × 5.5 inches) at 10 feet long needs (1.5 × 5.5 × 10) / 12 = 6.875 board feet per piece, or 330 board feet total — a figure a lumberyard uses to generate a bulk quote, since dimensional softwood framing lumber is often priced per board foot or per thousand board feet (MBF) for large orders even though it is sold by nominal size at the counter.
Sawmills selling rough-cut flitches use the same math on the sell side. A 5/4 rough board (actual 1.25 inches) that is 12 inches wide and 10 feet long comes to (1.25 × 12 × 10) / 12 = 12.5 board feet; at a mill price of $6.75 per board foot for a figured hardwood species, that single board costs $84.38 — which is why sawyers measure and tag each board's board footage individually rather than pricing by the piece.
Common misconceptions
"A 2x4 measures 2 inches by 4 inches." Not after milling. The 2x4 label is the nominal (rough-sawn) size; once the board is dried and surfaced (S4S), it actually measures 1.5 by 3.5 inches. Board foot calculations should always use the actual dimensions, not the nominal ones, or the volume estimate will run high.
"Board feet and linear feet are basically the same thing." They measure different things entirely. Linear feet is just length, ignoring width and thickness — useful for uniform stock like trim or fencing. Board feet is a volume measurement (thickness × width × length ÷ 12), which is why hardwood of varying widths is priced by the board foot rather than the linear foot.
Related calculators
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to 1 inch thick x 12 inches wide x 12 inches long (144 cubic inches). It is the standard measurement for buying hardwood lumber in North America.
How do I convert board feet to cubic feet?
One board foot = 1/12 of a cubic foot. To convert, divide board feet by 12. A 144-board-foot stack of lumber equals 12 cubic feet.
What is the difference between nominal and actual dimensions?
Nominal dimensions are the rough-sawn size before planing. Actual dimensions are the finished size. A 2x4 is actually 1.5 x 3.5 inches. The calculator uses actual dimensions for accuracy.
How many board feet are in a tree?
A mature oak tree might contain 200-500 board feet of usable lumber. The Doyle and International 1/4-inch log rules estimate board foot yield from log diameter and length.
Sources & references
This tool uses standard formulas and reference values from:
- • American Concrete Institute — ACI 318, Building Code Requirements for Structural Concrete. concrete.org
- • ICC — International Residential Code (IRC), span, footing and framing tables. codes.iccsafe.org
- • APA – The Engineered Wood Association, allowable span and load guidance.
Estimates for planning only. Span, load and code values vary by jurisdiction — verify against your local adopted code and a licensed engineer before building.