Lumber calculator
Board Foot Calculator
Multiply actual thickness in inches by actual width in inches by length in feet, divide by 12, and multiply by quantity. Add waste only after the raw board-foot total.
Planning estimate, not a contractor quote. Review the assumptions and replace presets with local prices when available.
Method
How this calculator works
A board foot is a volume measure used for hardwood and rough lumber. One board foot represents a piece 1 in thick, 12 in wide, and 12 in long. Board feet are not the same as linear feet, and nominal construction-lumber names should not be substituted for actual dimensions without checking.
Board feet = thickness in inches × width in inches × length in feet ÷ 12 × quantity. Purchasing board feet = raw board feet × (1 + waste). Material cost = purchasing board feet × price per board foot.
Worked example
A realistic starting point
Ten boards measuring an actual 1 in × 6 in × 8 ft total 40 BF. With 10% waste, plan for 44 BF. At $6 per BF, the material estimate is $264.
What changes the answer
Factors worth checking
Actual dimensions
Measure the board or use the seller’s stated actual dimensions. A nominal 1×6 is not necessarily a full 1 in × 6 in.
Rough vs surfaced lumber
Thickness and width can change during drying and surfacing. Buy enough rough stock to reach the required finished size.
Grade and defects
Knots, checks, sapwood, color matching, and grain selection affect usable yield and the appropriate waste allowance.
Seller tally rules
Dealers may round thickness, length, or tally according to industry practice. Compare the calculator with the invoice method.
Common questions
Board feet FAQ
What is one board foot?
It is 144 cubic inches of wood, commonly visualized as 1 in × 12 in × 12 in.
Is a board foot the same as a square foot?
No. A board foot includes thickness and measures volume; a square foot measures surface area.
Should I use nominal or actual dimensions?
Use actual dimensions unless the seller clearly states a specific tally convention.
How much waste should I add?
It depends on grade, defects, color matching, cut list, grain direction, and milling. Furniture parts often need more selection allowance than simple construction.
Evidence
Sources & review
- American Hardwood Export Council Species GuideIndustry board-foot measurement reference.
Published by Calcstead. Report a correction.
Method and source links reviewed September 4, 2026. Price presets are editable planning inputs and should be replaced with current local information.