Board Feet Calculator
Calculate board feet for any lumber order by quantity, thickness, width and length - the standard unit hardwood is sold in.
The board feet calculator returns the total board feet for any lumber order - the standard unit hardwood and rough lumber is priced in. One board foot = 1 in thick x 12 in wide x 12 in long = 144 cubic inches. The formula: board feet = (thickness_in x width_in x length_ft) / 12. Hardwood is sold by the rough thickness (4/4 = 1 inch, 5/4 = 1.25 inch, 6/4 = 1.5 inch, 8/4 = 2 inch), with the actual surfaced thickness about 1/4 inch less after dressing. Construction lumber is usually sold by the piece (a 2x4x8 is one stick, not by board foot), but project lumber, hardwood, and rough-sawn lumber are almost always priced per board foot.
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Frequently asked questions
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. Example: a 1 in thick x 6 in wide x 8 ft long board = (1 x 6 x 8) / 12 = 4 board feet. For multiple pieces, multiply by quantity. For thickness use the nominal (rough) thickness - 4/4 = 1 in, 5/4 = 1.25 in, 8/4 = 2 in. A 2x4x8 ft construction stud is technically 5.33 bdft (1.5 x 3.5 x 8 / 12 using actual dimensions) but lumberyards calc it as 5.33 bdft using nominal dimensions.
Yes - the math: (2 x 4 x 1) / 12 = 0.667 board feet. A 2x4x8 ft stud is 5.33 board feet. A 2x6x8 ft = 8 board feet. A 2x10x16 ft = 26.67 board feet. Board feet measures volume of wood, not surface area - thickness matters.
Hardwood comes in random widths and lengths from the sawmill - one 4/4 walnut board might be 5 in wide and 7 ft 3 in long, the next 8 in wide and 9 ft 11 in long. Pricing by board feet handles this variability fairly. Construction lumber is dimensional - every 2x4x8 ft is identical, so per-piece pricing is simpler. Some lumberyards quote both ways for the same product.
Rough hardwood is sawn to a nominal thickness with no planing. 4/4 rough is 1 inch thick; 8/4 rough is 2 inches thick. Surfaced lumber (S2S = surfaced two sides, S4S = surfaced all four sides) is planed flat and parallel after sawing - the planing removes about 1/4 inch total. So 4/4 surfaced (S2S) typically ends up 13/16 to 7/8 in thick. Pay attention when buying - some yards quote rough thickness, some surfaced.
Construction lumber (SPF, Doug fir, southern pine 2x stock): $1-2 per board foot in normal markets, $3-6 during shortages. Cabinet-grade pine: $2-4. Red oak: $4-7. Walnut: $7-15. Hard maple: $5-10. Cherry: $6-12. Premium specialty woods (curly maple, bird's-eye, figured walnut): $20-50+ per board foot. Always factor in waste (10-20% for project lumber) and yield (4/4 surfaces down to 13/16 actual).