The Calculator Helper

Board Feet Calculator

Calculate lumber board feet and cost from board dimensions.

in
in
ft
$
Total board feet
—
Per board
—
Quantity
—
Total cost
—
Cost per board
—

Board feet are usually figured on nominal (rough-sawn) sizes. Length is in feet; thickness and width in inches.

Measuring lumber by volume

Hardwood is sold by the board foot — a volume measure rather than a length — so boards of different sizes can be priced fairly. One board foot is a piece 12 inches square and an inch thick.

board feet = thickness(in) × width(in) × length(ft) ÷ 12 × quantity

Working with length in feet folds the inch conversion neatly into a single divisor of 12. Add a price per board foot and the calculator totals the cost of your cut list.

Worked example

Five boards measuring 1 in thick, 6 in wide and 8 ft long come to 4 board feet each — 20 board feet in total. At $5 per board foot that is $100 of lumber.

Buying timber wisely

Pricing in board feet lets you compare a thick, narrow plank against a thin, wide one on equal footing. Plan your cut list, add a margin for defects and offcuts, and the board-foot total tells you what to order and roughly what it will cost.

Workshop notes

  • Nominal sizes. Pricing usually uses rough dimensions, not planed ones.
  • Add for waste. Knots, splits and cuts mean buying a little extra.
  • Volume, not length. Board feet reflect thickness and width too.

Frequently asked questions

What is a board foot?
A unit of lumber volume equal to a piece 12 inches square and 1 inch thick (144 cubic inches). It is the standard way hardwood is priced and sold in North America.
What is the formula?
Board feet = thickness (in) × width (in) × length (ft) ÷ 12, multiplied by the number of boards. Using length in feet folds the 12-inch conversion into the divisor.
Do I use nominal or actual size?
Board feet are usually figured on nominal (rough) dimensions before planing. A “1×6” is treated as a full inch by six inches for pricing, even though the finished size is smaller.
How does this relate to linear feet?
Linear feet just measures length and ignores thickness and width. Board feet captures the full volume, so it is the fairer basis for comparing differently sized boards.