How this board foot calculator works
A board foot is the standard way lumber yards measure and price wood by volume. One board foot is the amount of wood in a piece that is one foot long, one foot wide and one inch thick — 144 cubic inches. Because it is a volume, a thicker or wider board contains more board feet even if its length is the same.
This calculator uses the imperial board foot formula. When you enter the length in feet it computes (thickness × width × length ft) ÷ 12; when you switch the unit to inches it uses (thickness × width × length in) ÷ 144. It then multiplies by the quantity of identical boards for the total, and — if you supply a price per board foot — multiplies the total board feet by that price for an estimated cost.
Metric note: if your dimensions are in centimetres, multiply thickness × width × length in cm to get cubic centimetres, then divide by 2,359.74 (the number of cm³ in a board foot) to convert. This calculator shows that metric equivalent alongside the imperial result.
Frequently asked questions
- What is a board foot?
- A board foot is a unit of lumber volume equal to a piece 1 foot long, 1 foot wide and 1 inch thick — that is 144 cubic inches. It measures how much wood you are buying, regardless of the board's actual shape.
- How do I calculate board feet?
- Multiply thickness in inches by width in inches by length in inches and divide by 144. If the length is given in feet, multiply thickness by width by length in feet and divide by 12. Then multiply by the number of identical boards for the total.
- Is a board foot the same as a linear foot?
- No. A linear foot measures only length, ignoring thickness and width. A board foot measures volume, so two boards of the same length can contain very different board footage if their thickness or width differs.
- How do I include cost?
- Lumber is often priced per board foot. Enter a price per board foot and the calculator multiplies it by the total board feet to give an estimated total cost. Leave the price blank to see board footage only.
- Does nominal vs actual size matter?
- It can. Rough lumber is usually sold by nominal dimensions, but surfaced (planed) boards are smaller than their nominal size — a nominal 2x4 actually measures about 1.5 by 3.5 inches. Use nominal sizes for pricing and actual sizes when you need a precise volume.
- How many board feet in a 2x4x8?
- Using nominal dimensions, a 2 inch by 4 inch by 8 foot board is (2 × 4 × 8) ÷ 12 = 5.33 board feet. The same length expressed in inches, 96 inches, gives (2 × 4 × 96) ÷ 144 = 5.33 board feet.