Board Foot Calculator
Calculate board-foot lumber volume from thickness, width, length, equal-piece count, units, and explicit waste.
Content updated August 6, 2026
A board foot is a volume, not linear length or surface area. Use the dimension basis used for the transaction—actual and nominal dressed dimensions differ—and do not use this lumber formula to scale logs.
Calculate board-foot volume for equal pieces of lumber from thickness, width, length, and count. Cross-section and length units are selected separately, supporting measurements such as inches by inches by feet or centimetres by metres.
The result keeps net piece volume separate from an optional waste allowance and also shows cubic feet, cubic metres, and total linear length. No nominal-to-actual lumber conversion is inferred.
The Board Foot formula
Board feet per piece = thickness(in) × width(in) × length(ft) ÷ 12 · net board feet = per-piece board feet × piecesOrder board feet = net board feet × (1 + waste% ÷ 100) · cubic feet = board feet ÷ 12.
Worked example
One 1 in × 6 in × 8 ft piece contains 4 board feet. Ten equal pieces contain 40 board feet; adding 10% explicit waste gives 44 board feet or about 3.667 cubic feet.
Assumptions, rounding, and limitations
Assumptions
- Every counted piece is a rectangular prism with equal dimensions.
- Entered dimensions use the measurement basis relevant to the calculation.
- Waste is an optional percentage of net rectangular lumber volume.
- One board foot equals exactly 144 cubic inches.
Rounding: Board-foot and converted volume calculations retain full floating-point precision. Displays use up to five decimals; no supplier increment or piece count is rounded automatically.
Limitations
- Does not infer nominal versus actual, rough versus surfaced, moisture, shrinkage, kerf, defect, grading, price, weight, density, species, or stock-length optimization.
- Does not implement log scaling or predict recoverable lumber from logs, trees, slabs, tapered pieces, or irregular shapes.
Sources
- Production, Prices, Employment, and Trade in Northwest Forest Industries — U.S. Forest Service Pacific Northwest Research Station
- NIST Guide to the SI, Appendix B.9: Conversion Factors — National Institute of Standards and Technology
A board foot is a defined volume
The U.S. Forest Service defines one board foot as a volume measuring 12 inches by 12 inches by 1 inch, or 144 cubic inches. For dimensions in inches and length in feet, board feet equal thickness × width × length ÷ 12.
One board foot is one-twelfth of a cubic foot. The calculator uses exact international-foot conversions for metric displays rather than a rounded lumber-market conversion factor.
State the dimension basis before comparing lumber
Nominal, rough, green, surfaced, and finished dimensions can differ. The formula calculates the dimensions entered; it does not decide whether a supplier invoices from nominal or actual measurements.
Board-foot measurement of individual lumber pieces is different from log scaling rules such as Doyle, Scribner, or International 1/4-inch. Do not use this rectangular-piece result as a log recovery estimate.
Frequently asked questions
▶What is one board foot?
It is a lumber volume equivalent to 12 inches × 12 inches × 1 inch, or 144 cubic inches.
▶What is the board-foot formula?
With thickness and width in inches and length in feet, board feet equal thickness × width × length ÷ 12.
▶Should I enter nominal or actual dimensions?
Use the dimension basis relevant to the supplier, inventory, or project. The calculator does not convert nominal sizes into dressed actual sizes.
▶How many cubic feet are in a board foot?
One board foot is one-twelfth of a cubic foot because it contains 144 cubic inches and a cubic foot contains 1,728 cubic inches.
▶Can this calculate board feet in a log?
No. Log scaling depends on a selected log rule and recovery assumptions. This calculator models rectangular lumber pieces only.
Related calculators
Estimate posts, equal intervals, and horizontal rail length for one or more independent straight fence runs.
Open calculator →Calculate and convert volumes for seven common prisms, round solids, cubes, and pyramids.
Open calculator →Calculate the total square footage of one or more equal rectangles with exact metric conversions.
Open calculator →Disclaimer: Board Foot Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.