πͺ΅ Board Feet Calculator
Board feet, total volume, and cost for any lumber order.
Total Board Feet
How to Use This Calculator
Enter the nominal thickness, width, and length of the boards you need, plus the quantity and (optionally) the price per board foot your supplier quoted. The calculator converts everything to board feet, totals your order, and estimates the cost. Enter dimensions in inches for thickness and width, and feet for length.
Enter the nominal size of the board: a 2x6 means 2 inches thick and 6 inches wide. Enter length in feet, for example 8 for an eight-foot board.
Enter how many boards you need. Do not forget a waste factor: add 10 to 15 percent to your count for cutting waste and mistakes before entering the quantity.
Enter the price per board foot if you have a quote. Hardwood dealers and sawmills price this way, so this field gives you the real order total.
Compare quotes by running each supplier's per-board-foot price through the same size and quantity. The cheapest per-board price is not always the cheapest per board foot.
The Board Foot Formula
The divisor 144 is the number of cubic inches in a board foot. The formula treats the board as a rectangular block, so it works for any size: a 1x12x12 contains exactly 1 board foot, and a 2x4x8 contains 5.33 board feet. Because the lumber trade calculates on nominal dimensions, you get the same number your supplier uses, which keeps your estimates and their invoices in agreement.
Price per board foot varies wildly by species, grade, and surfacing. Construction-grade pine might run under a dollar per board foot, while figured walnut or white oak can run five to ten dollars or more. Rough-sawn lumber is cheapest per board foot but you pay for the waste: you lose about a quarter inch of thickness when you plane it smooth, and you lose width trimming defects.
Worked Example
You need twenty 2x6x8 boards at $1.50 per board foot. First convert length to inches: 8 feet = 96 inches. Board feet per board = (2 x 6 x 96) / 144 = 1,152 / 144 = 8 board feet. Total = 8 x 20 = 160 board feet. Cost = 160 x $1.50 = $240. Add 15 percent for waste and you would order 23 boards: 184 board feet for $276.
Another common case: ten 1x8x10 pine boards at $1.10 per board foot. Each board is (1 x 8 x 120) / 144 = 6.67 board feet. Ten boards = 66.7 board feet, costing about $73.37.
Tips for Buying Lumber
Sort and cull before you pay when you buy in person. Check each board for bow, cup, twist, and knots, and reject anything you would not use. Sight down the length of the board like a rifle barrel; even a small bow becomes a big problem in a long shelf or table apron. For hardwood, learn the grade names: FAS and Select are the top grades with the highest percentage of clear, usable wood, while #1 Common has more defects but costs much less and is perfect for painted or rustic projects.
Ask whether the price is for rough, S2S, or S4S stock. A quote that looks cheap may be rough-sawn, meaning you do the milling and absorb the waste. And for large orders, ask about quantity discounts: many yards cut a better per-board-foot price once you cross 100 or 500 board feet.
Frequently Asked Questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches: a board 1 inch thick, 12 inches wide, and 12 inches long. The formula is (thickness in inches x width in inches x length in inches) / 144. Lumber is bought and sold by the board foot at hardwood dealers and most sawmills.
Should I use nominal or actual dimensions?
Use nominal dimensions, the name sizes like 2x4 or 1x8. That is the industry standard for board-foot calculations. A nominal 2x4x8 (actually 1.5 x 3.5 inches) is calculated as 2 x 4 x 96 / 144 = 5.33 board feet. Your supplier prices the same way, so nominal keeps you consistent.
How much extra lumber should I buy?
Buy 10 to 15 percent extra for normal projects to cover cutting waste and layout mistakes. If you are working with rough-sawn lumber that has knots, checks, or wane along the edges, bump that to 20 to 30 percent, because you will lose stock ripping around defects. It is cheaper to have one extra board than to make a second trip.
How do I compare lumber prices between suppliers?
Convert every quote to price per board foot. A $24 2x6x8 is 8 board feet, so $3.00 per board foot. Compare that against another supplier's per-board-foot price on the same species and grade. This calculator does the conversion for you: enter your price per board foot to see the total for any size and quantity.
What does S4S or S2S mean on a lumber quote?
S4S means surfaced on four sides: the board has been planed smooth on all faces and edges, which is what you want for furniture and trim. S2S is surfaced on two sides (the faces) with rough edges, often cheaper. Rough-sawn lumber is cheapest per board foot but you lose thickness when you mill it yourself.