Board Foot Calculator
Convert lumber dimensions into board feet and total cost — the unit hardwood is sold in.
What you need
4.0
Total board feet — Thickness × width × length ÷ 144, with each dimension in inches.
- Board feet per board
- 4.0
- Total cubic feet
- 0.3
- Total linear feet
- 8.0 ft
Estimates for planning. Confirm quantities with your supplier before ordering — see the assumptions below for the figures used.
How to use the board foot calculator
A board foot is 144 cubic inches of wood: one foot square by one inch thick. Hardwood dealers price by the board foot, which makes comparing a 4/4 board against a 8/4 board impossible by eye. Enter your dimensions and quantity to get the total.
What this calculator assumes
Every estimate depends on figures that vary by supplier and conditions. These are the ones used here, so you can sanity-check the result against your own quote.
- A board foot is 144 cubic inches — 12 in × 12 in × 1 in. The formula is thickness × width × length in inches, divided by 144.
- Hardwood is normally priced on rough (pre-surfacing) dimensions, so a board sold as 4/4 measures about 1 inch before planing and roughly 13/16 in after. Use the rough figure when pricing.
- Softwood dimensional lumber is sold by the piece, not the board foot. Use the lumber calculator for that.
- Waste is not included by default. For rough stock with defects, adding 20–30% is normal practice.
Frequently asked questions
How do you calculate board feet?
Multiply thickness × width × length with every measurement in inches, then divide by 144. A board 1 in thick, 6 in wide and 96 in (8 ft) long is 1 × 6 × 96 ÷ 144 = 4 board feet. If you have the length in feet, the shortcut is thickness × width × length(ft) ÷ 12.
What does 4/4 mean in lumber?
It is thickness in quarter-inches, so 4/4 (spoken 'four quarter') is 1 inch, 6/4 is 1½ inches and 8/4 is 2 inches. It refers to rough thickness before surfacing — a 4/4 board planed on both faces ends up around 13/16 inch.
Is a board foot the same as a linear foot?
No. A linear foot is just length, ignoring thickness and width. A board foot is a volume. Two boards can be the same linear footage and differ threefold in board feet — which is exactly why hardwood is priced this way.
How much extra hardwood should I buy?
Twenty to thirty percent over your finished requirement. Rough boards have defects to cut around, edges to joint straight, and you lose thickness to planing. For figured or highly-selected stock, more.
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