OnSumoTools

Lumber Board Foot Calculator

One board foot is a piece 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). Hardwood lumber is often priced per board foot.

Units

Lumber pieces

Project settings

Raw board feet

16.00

With 15% waste

18.40

Estimated cost

$82.8

Board-by-board breakdown

PieceQtyTWLBF eachBF total
Shelf slatsOak41 in6 in8 ft4.0016.00

Board foot totals are estimates. Confirm grade, surfacing, and pricing with your supplier before you order.

How does the Board Foot Calculator work step by step?

Enter thickness, width, and length for each lumber piece, set quantity, then add a waste percent for cuts and defects. The calculator sums board feet and applies waste once on the project total.

What does a typical Board Foot Calculator result look like?

Four shelf slats at 1 by 6 by 8 feet each are 4 board feet per piece, or 16 board feet raw. With 15% waste that is 18.4 board feet to buy.

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Frequently asked questions

  • What is a board foot?

    A board foot is a volume measurement for lumber equal to a piece that is 1 inch thick, 12 inches wide, and 12 inches long. Hardwood dealers and specialty lumber yards almost always quote price per board foot rather than per piece, so knowing how to calculate board feet is essential for estimating material cost before you buy.

  • Why do I need a waste factor?

    Raw boards contain knots, checks, twist, and other defects that reduce usable yield. Every cut also removes material as sawdust. Many shops add 15 to 20 percent waste on top of their net board foot calculation. Projects with figured grain, complex joinery, or tight color matching may need 25 percent or more to account for selective cutting.

  • Do softwood 2x4s use board feet?

    Dimensional softwood lumber sold at home improvement stores is priced by the linear foot or per individual piece, not by board feet. Board foot pricing is standard at hardwood yards and specialty suppliers selling species like oak, maple, walnut, and cherry. If you are ordering from a hardwood dealer, always confirm which unit the price quote refers to.

  • Can I mix board sizes in one project?

    Yes. Add one row for each different board dimension in your project. The calculator shows board feet per piece and a row subtotal for each size, then combines all rows into a single project total with your waste factor applied. This lets you price out a mixed lumber order with one calculation rather than running separate estimates.

What a board foot actually is

Hardwood isn't sold by the plank. It's sold by the board foot, a volume equal to a piece 1 inch thick, 12 inches wide and 12 inches long. That's 144 cubic inches.

To get it, multiply thickness in inches by width in inches by length in feet, then divide by 12. A board 2 inches thick, 8 wide and 10 feet long comes to about 13.3 board feet. The calculator does this for every row you add, so you don't have to redo it on a scrap of paper.

Adding up a whole project

Real projects use boards of different sizes. Add a row for each, enter the quantity and the tool totals the board feet. You can also set a price per board foot to see the cost.

Lumber yards often quote rough sizes, like 4/4 or 8/4. Those are quarters of an inch, so 4/4 is 1 inch and 8/4 is 2 inches. Rough boards get planed down, so you lose some thickness. If your plan needs a finished 3/4 inch, buy 4/4 and expect it to just make it.

  • Measure thickness before milling, not after
  • Round up lengths to what the yard actually stocks
  • Ask if the price is for rough or surfaced stock

Don't skip the waste factor

Every cut loses wood to the saw blade, knots, checks and end splits. A common starting point is 10 to 15 percent extra for simple projects and 20 percent or more for fine furniture where you pick around defects and match grain.

Set the waste in the tool and it adds that to the total. It's cheaper to buy a bit extra now than to go back for a single board that doesn't match the color of the rest.

A worked example

Say you're building a dining table. You want four legs cut from 8/4 stock at 3 inches wide and 30 inches long, plus a top made from six boards, 4/4 thick, 6 inches wide and 7 feet long.

The legs: 2 x 3 x 2.5 feet, divided by 12, is 1.25 board feet each. Four of them is 5. The top boards: 1 x 6 x 7, divided by 12, is 3.5 each, so 21 for six. That's 26 board feet before waste. Add 20 percent and you'd buy about 31.

At 9 dollars a board foot, that's around 280. Seeing it before you walk into the yard keeps surprises off the receipt.

Common buying mistakes

Forgetting that width counts too. A narrow board has fewer board feet than a wide one of the same length, so the price per piece can look odd.

Another trap is measuring finished sizes when the yard sells rough ones. Rough boards are a bit thicker and wider than the final piece, which is the whole point. Ask for the actual dimensions before you cut a list.

And don't forget moisture. Wood that isn't dry enough will move after you build with it. Buy kiln-dried stock for furniture and let it rest in your shop for a week or two.

Softwood is different

Construction lumber like a 2x4 is sold by the piece or by the linear foot, not by the board foot. The name is also a lie: a 2x4 is really about 1.5 by 3.5 inches. Use this tool for hardwoods and specialty boards, where price per board foot is the norm.

Everything stays in your browser, so try as many versions of the cut list as you like.