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Board Foot Calculator

Convert lumber dimensions to board feet and price a material order.

Dimensions

Quarter notation is rough thickness before surfacing, and that is the thickness you are billed for.

in

Hardwood is measured at actual width, which is why the invoice rarely lands on a round number.

ft
Length is measured in
Order
$/bf

Leave at zero to skip the cost estimate.

One board foot is 144 cubic inches: thickness × width × length in inches, divided by 144. A board foot is a volume, not an area, so a 4/4 board 6 inches wide and 8 feet long and a 8/4 board 3 inches wide and 8 feet long are both 4 board feet.

Total board feet

40.00board feet

4.000 board feet per piece × 10 pieces.
Board feet per piece1.000" × 6.000" × 96.00" ÷ 144
4.000
Total costAt $6.50 per board foot
$260.00
Cost per piece
$26.00
Estimated weightKiln-dried hardwood at roughly 44 lb per cubic foot
147 lb
The same quantity expressed other ways
MeasureQuantityHow it is derived
Board feet40.00Thickness × width × length in inches ÷ 144
Cubic inches5,76040.00 bf × 144
Cubic feet3.3340.00 bf ÷ 12
Lineal feet of stock80.010 pieces × 8.00 ft
Surface measure (face area)40.0 sq ftWidth × length, ignoring thickness
Equivalent 1× stock 6" × 8'10.0 boardsEach is 4.00 board feet
Equivalent 2×4 × 8' nominal7.5 sticksEach is 5.33 board feet on nominal dimensions
Estimated weight147 lb44 lb per cubic foot, kiln dried
Material total$260.00

Order more than you measure

Board foot math gives you the volume in the pile, not the volume you can use. Rough hardwood loses width to jointing and length to checked or bowed ends, and a board with wane on one edge yields less than its tally. Most shops add 20 to 30% for a project with defined parts, more when the parts have to match for grain or color.

Softwood dimensional lumber is calculated on nominal dimensions — a 2×4 is billed as 2 by 4 even though it measures 1-1/2 by 3-1/2. Hardwood is the opposite and is calculated on actual measured width against rough thickness. This tool uses whatever you type, so enter nominal figures for construction lumber and measured figures for hardwood.

What this assumes

  • One board foot equals 144 cubic inches: thickness × width × length in inches, divided by 144.
  • Hardwood is priced on rough thickness in quarters, so 4/4 stock is billed as one inch even after surfacing.
  • Softwood dimensional lumber is calculated on nominal, not actual, dimensions.

Understanding the result

Quarter notation

Hardwood thickness is expressed in quarter inches: 4/4 is one inch, 8/4 is two inches. Lumber is measured and billed at its rough thickness before surfacing, so 4/4 stock that arrives at 13/16 inch is still sold and calculated as a full inch.

Nominal versus actual

A 2×4 measures 1.5 by 3.5 inches, but board foot calculations for construction lumber use the nominal 2 by 4. Hardwood is the opposite — it is calculated on actual measured width, which is why hardwood invoices rarely come out to round numbers.

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