Lumber Calculator to estimate boards, linear feet, board feet, cubic volume, waste allowance, material cost, tax, and total project cost for dimensional lumber.
Home & Construction Calculators
Calculate a supplier-ready dimensional-lumber order from board size, length, piece quantity, waste, and local pricing.
Board-foot calculations normally use nominal thickness and width. For physical volume, weight, fit, or structural design, confirm actual dressed dimensions, species, grade, moisture condition, treatment, and span requirements.
About the Lumber Calculator
This dimensional lumber calculator estimates whole boards to purchase, total linear feet, net and purchased board feet, cubic volume, material cost with sales tax, and a complete preliminary project total. Editable waste and cost assumptions make it useful for framing, carpentry, decking, and general woodworking estimates.
Formula and assumptions
Board feet per piece = nominal thickness in inches × nominal width in inches × board length in feet ÷ 12. Purchase pieces = net pieces × (1 + waste percentage ÷ 100), rounded up. Purchased linear feet = purchase pieces × board length. Purchased board feet = board feet per piece × purchase pieces. Cubic feet = purchased board feet ÷ 12. Material cost with tax = purchase pieces × price per board × (1 + tax percentage ÷ 100). Project total = taxed material cost + delivery, fasteners, labor, and extras.
Worked example
Twenty-four nominal 2 × 6 boards, each 8 ft long, contain 192 net board feet. Adding 10% waste requires 27 whole boards, totaling 216 linear feet, 216 board feet, and 18 cubic feet by nominal volume. At $9.50 per board plus 6% sales tax, materials cost $271.89. Adding $120 for delivery, fasteners, labor, and extras gives an estimated project total of $391.89.
Measurement checklist
- Count boards from a clear cut list or framing layout.
- Separate different dimensions, lengths, species, and grades.
- Confirm whether supplier pricing is per piece, linear foot, or board foot.
- Choose waste for cuts, defects, matching, and site conditions.
- Confirm stock lengths before finalizing the order.
Board feet versus linear feet
Linear feet measure length only. Board feet measure nominal lumber volume: one board foot equals a board 1 inch thick, 12 inches wide, and 1 foot long. Finished lumber is usually smaller than its nominal dimensions, so board feet are mainly a purchasing and pricing convention.
Manual calculation steps
- Calculate board feet for one piece.
- Multiply by net pieces for the project requirement.
- Apply waste and round to whole boards.
- Multiply purchase pieces by length for linear feet.
- Calculate purchased board feet and cubic feet.
- Apply price and tax, then add project extras.
Frequently asked questions
Should I use nominal or actual dimensions?
Use nominal dimensions for standard board-foot purchasing calculations. Use actual measured dimensions for physical volume, fit, weight, and fabrication checks.
How much lumber waste should I add?
Simple straight-cut projects may need 5% to 10%, while complex layouts, visual matching, defects, and uncertain site conditions can require more.
Can this calculator size structural members?
No. It estimates quantities and costs only. Beam, joist, stud, rafter, and connection design requires approved span tables or engineering.
Common mistakes
- Mixing nominal and actual board dimensions.
- Combining different board lengths into one line item.
- Rounding before applying the waste allowance.
- Ignoring unusable defects and required cut lengths.
- Using quantity calculations as structural approval.