What is a board foot?

A board foot is a unit of lumber volume equal to 144 cubic inches, which is a board 1 inch thick, 12 inches wide and 1 foot long. Hardwood lumberyards sell by the board foot. Framing lumber like 2x4s is usually sold by the piece, but board feet are how you compare prices across different sizes and lengths.

How do you calculate board feet?

Multiply thickness in inches by width in inches by length in feet, then divide by 12. One 2x6 that is 8 feet long is 2 × 6 × 8 = 96, and 96 ÷ 12 = 8 board feet. Multiply by the number of pieces to get the total.

How many board feet are in a 2x4, 2x6, 2x8, 2x10 and 2x12?

For an 8-foot piece, a 2x4 is 5.33 board feet, a 2x6 is 8, a 2x8 is 10.67, a 2x10 is 13.33 and a 2x12 is 16. Each size holds a fixed number of board feet per linear foot: 0.67 for a 2x4, 1 for a 2x6, 1.33 for a 2x8, 1.67 for a 2x10 and 2 for a 2x12.

How do you convert linear feet to board feet?

Multiply the linear feet by thickness × width ÷ 12, using the nominal size in inches. For a 2x6 that factor is exactly 1, so 100 linear feet of 2x6 is 100 board feet. For a 2x4 the factor is 0.667, so 100 linear feet is about 66.7 board feet.

Do I use the nominal size or the actual size?

Use the nominal size, the name on the tag. A 2x6 measures about 1.5 by 5.5 inches after it is dried and planed, but it is still figured and priced as 2 by 6. Using the smaller actual size would understate the board feet compared with what the lumberyard charges.

How much waste should I add to a lumber order?

Ten percent is a common allowance for straight cuts from good stock. Plan on 15 to 20 percent when the stock has crooks, checks or knots you will cut around, or when the project has a lot of angled cuts. This calculator adds your waste percentage to the board feet and to the cost.

Is my data stored anywhere?

No. All calculations run locally in your browser. Nothing you enter is transmitted to a server or stored.

AI Insights

Board Foot Calculator

Find the board feet in any lumber order from its size, length and quantity, convert linear feet to board feet, and see what it will cost with waste.

Last updated October 23, 2026

Lumber size (nominal)

Actual size is about 1-1/2" x 5-1/2". Board feet use the nominal size.

Length of each piece

Number of pieces

Waste (%)

Price per board foot (optional)

Board feet

88 bf with 10% waste

Board feet per piece	8 bf
Board feet per linear foot	1 bf
Total linear feet	80 ft

You are pulling a stack of framing studs for a shed wall or workshop partition. At this volume, remember that big box stores and lumberyards sell dimensional lumber by the individual piece rather than the calculated board foot, so use this total primarily for estimating your material costs and vehicle capacity. Because dimensional lumber shrinks during drying, make sure to buy an extra ten percent to account for the inevitable warped, cracked, or knot-heavy boards you will need to cull at the pile.

AI-generated insight

How to use the board foot calculator

1
Pick the lumber size from the list, such as a 2x6 or 4x4. For a hardwood board or an odd size, choose Custom and type the thickness and width in inches.
2
Enter the length of each piece in feet or inches and the number of pieces. Leave the waste at 10% or change it.
3
Add a price per board foot if you want a cost. Already know your linear feet? Switch to the second tab to convert it straight to board feet.

How board feet are calculated

One board foot is a board 1 inch thick, 12 inches wide and 1 foot long. For any other board, multiply thickness by width by length, then divide by 12.

Formula: board feet = thickness (in) × width (in) × length (ft) ÷ 12. The 12 comes from the definition: a board foot is 144 cubic inches, and a board 1 inch thick and 12 inches wide has a 12-square-inch cross-section, so each foot of its length adds up to 144.

Worked example: ten 2x6 boards, each 8 feet long. One board is 2 × 6 × 8 ÷ 12 = 8 board feet, so ten boards are 80 board feet. Adding 10% waste brings the order to 88 board feet. At $4.50 per board foot that comes to $396.

Nominal, not actual: lumber is counted on the size it is named, not the size you measure. A 2x6 is about 1.5 by 5.5 inches once it has been dried and planed, yet it is figured as 2 by 6. The calculator shows the actual size under the size picker for reference only.

Board feet in a 2x4, 2x6, 2x8, 2x10 and 2x12

Size	8 ft	10 ft	12 ft	16 ft
2x4	5.33 bf	6.67 bf	8 bf	10.67 bf
2x6	8 bf	10 bf	12 bf	16 bf
2x8	10.67 bf	13.33 bf	16 bf	21.33 bf
2x10	13.33 bf	16.67 bf	20 bf	26.67 bf
2x12	16 bf	20 bf	24 bf	32 bf

Board feet per single piece at each common stock length. Multiply by the number of pieces for an order total.

Linear feet to board feet

Every nominal size holds a fixed number of board feet per linear foot: thickness × width ÷ 12. That makes a 2x6 handy, since it works out to exactly 1, so linear feet and board feet are the same number. A 2x4 holds 0.67 board feet per linear foot, a 2x8 holds 1.33, and a 2x12 holds 2.

Example: a lumber list calls for 240 linear feet of 2x8. That is 240 × 1.33 = 320 board feet. To go the other way, divide board feet by the same factor: 320 ÷ 1.33 gives back 240 linear feet. For a longer walkthrough, see how to convert linear feet to board feet.

Everyday uses for a board foot calculator

Pricing a hardwood order. Lumberyards quote oak, walnut and maple by the board foot, so you need the total before you can compare quotes.
Comparing lumber prices. A 2x10 and a 2x6 are priced per piece, but dividing by board feet shows which one is actually cheaper per unit of wood.
Building a deck, shed or fence. Add up joists, posts and rails across sizes to see the total volume before you head to the yard.
Framing a wall. Studs and plates add up quickly. Our Wall Framing Calculator counts the pieces, and this page turns any size and length into board feet.

Building a deck? Our Deck Material Calculator → works out boards, joists, screws and cost for the whole project.

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