What the Lumber Calculator Does
This Lumber Calculator works out how much wood you have in three different units at once: board feet, cubic feet, and cubic meters. It is built around the board-foot measurement system used widely in the United States and Canada for buying and pricing rough and dimensional lumber. Enter the dimensions of a single board and the number of boards, and the calculator returns the total volume for the whole batch — handy for estimating material costs, planning a delivery, or comparing quotes.
The Input Fields
- Length (feet) — the length of one board measured in feet.
- Width (inches) — the face width of the board in inches.
- Thickness (inches) — how thick the board is, in inches.
- Quantity — how many identical boards you are calculating.
Note the mixed units: length is entered in feet while width and thickness are in inches. This matches how lumber is traditionally described (for example, a "2×4×8" board).
The Formula
The core calculation is the standard board-foot formula:
- Board feet = (Length × Width × Thickness × Quantity) ÷ 144
- Cubic feet = Board feet ÷ 12
- Cubic meters = Cubic feet × 0.0283168
The standard board-foot formula is:
The 144 divisor converts the mixed feet-and-inches figures into board feet (one board foot equals 144 cubic inches of wood, i.e. 1\ ft × 12\ in × 1\ in). Dividing by 12 turns board feet into true cubic feet, and the 0.0283168 factor converts cubic feet to cubic meters.
Worked Example
Suppose you have 10 boards, each 8 feet long, 6 inches wide, and 2 inches thick.
- Board feet = (8 × 6 × 2 × 10) ÷ 144 = 960 ÷ 144 = 6.67 board feet
- Cubic feet = 6.67 ÷ 12 = 0.556 cubic feet
- Cubic meters = 0.556 × 0.0283168 = 0.0157 cubic meters
You could then multiply the board feet by your supplier's per-board-foot price to estimate the cost.
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