Board Feet Calculator for a 2x4x8

How the board-foot total is calculated

The form expects thickness in inches, width in inches, and length in feet. Board feet for one piece = thickness × width × length ÷ 12. The piece count multiplies that. An empty count, or a count of 0, is treated as 1, because a missing or zero count is replaced before the multiply. Total board feet display to two decimal places. Board feet per piece display to three decimal places. If the price box has a number, cost = total board feet × price per board foot, rounded to the nearest dollar. If the price box is empty, cost displays as N/A. A price of 0 displays as $0. The page does not divide by 144. Length in inches does not belong in the length field. Convert inches to feet first. Thirty-six inches is 3 feet. Typing 36 in the length field makes the result twelve times too large.

A board foot is the volume of a piece 1 inch thick, 12 inches wide, and 1 foot long, which is 144 cubic inches. The ÷ 12 in the formula is that definition with thickness and width already in inches and length already in feet. The page does not look up a nominal size. The inches you type are the inches that get multiplied.

Worked examples

Example 1: A nominal 1×6, eight feet, at $6

Thickness 1, width 6, length 8, one piece, price 6. One piece = 1 × 6 × 8 ÷ 12 = 4. The total displays as 4 board feet, per piece as 4. Cost = 4 × 6 = $24. That $24 is the board-foot price times the volume. It is not tax, delivery, or milling.

Example 2: The same 2×4×8 typed two ways

Thickness 2, width 4, length 8, one piece: 2 × 4 × 8 ÷ 12 = 5.333…, so the total displays as 5.33 board feet and per piece as 5.333. Thickness 1.5, width 3.5, length 8: 1.5 × 3.5 × 8 ÷ 12 = 3.5 exactly, so both lines display 3.5. Ten pieces of the 2-by-4 typing, at $3.50 per board foot: per piece still displays as 5.333, and the total displays as 53.33 board feet. The unrounded total is 53.333… board feet. Cost = 53.333… × 3.50 = 186.666…, which displays as $187. The page does not decide whether the seller prices the nominal 2 by 4 or the dressed 1.5 by 3.5. You decide which inches to type. Measure, or read the quote.

Example 3: Rough 5/4 stock, and a blank price

Thickness 1.25, width 8, length 10, one piece, price left blank. 1.25 × 8 × 10 ÷ 12 = 8.333…, so the total displays as 8.33 board feet and per piece as 8.333. Cost displays as N/A, not as $0. Six pieces of 0.75 by 11.25 by 8 feet, at $5 per board foot: per piece = 0.75 × 11.25 × 8 ÷ 12 = 5.625, total = 33.75, cost = 33.75 × 5 = 168.75, which displays as $169. Those 0.75 and 11.25 figures are numbers you would type because you measured them. The form will not turn the words "1×12" into 0.75 and 11.25.

When to use this

Use it when a hardwood dealer, a mill, or a quote prices lumber by the board foot and you have the thickness, width, and length in the units the fields ask for. Use it to compare two quotes only after both quotes are using the same inches, nominal or measured. A sheet of plywood is sold by the sheet and by square feet, not by this formula. Area is the Square Footage Calculator. Paint on that sheet is the Paint Coverage Calculator. A concrete form beside the lumber pile is the Concrete Volume Calculator, in cubic yards. If the length is still in meters, convert to feet with the Length Converter before you type it. This form multiplies by the length as feet.

Waste is not in the formula

Unlike the sod calculator, which always multiplies area by 1.05, this page has no waste factor. The total is the pieces you typed. If you need extra for offcuts, increase the piece count or the length and write down that you did it. There is no standard percent hiding in the script. Adding a percent in your head and also padding the piece count counts the pad twice. Knots, grain matching, and a bad board are reasons you might buy more. They are not a number this page can see.

Price per board foot is optional and is whatever the quote says. The page does not know species, grade, or moisture. Two quotes at the same dollar per board foot are the same price per board foot. They are not the same project cost if one quote used nominal inches and the other used caliper inches. Run both sets of inches. The paint label article is about coverage on a can, which is a different unit problem of the same kind: the label's number, not a remembered average.

Common mistakes

• Putting length in inches. The length field is feet. A 36-inch board typed as 36 becomes twelve times the board feet of a 3-foot board.
• Expecting "2×4" to become 1.5 by 3.5. Typing 2 and 4 yields 5.33 board feet for an 8-foot piece. Typing 1.5 and 3.5 yields 3.5. The page does not substitute.
• Reading a blank price as free. Blank displays N/A. Zero displays $0.
• Typing 0 pieces and expecting zero. A count of 0 is replaced with 1. Clear the other fields if you want the panel reset.
• Multiplying rounded 5.33 by the price and expecting the cost line. Cost uses the unrounded total, then rounds to the nearest dollar. Ten nominal 2×4×8s at $3.50 display as 53.33 board feet and $187.
• Adding a waste percent the page already applied. It did not apply one. Pad the inputs once, or not at all.

Limitations

One cross-section and one length per calculation, a piece count, and an optional price per board foot. No nominal-size table, no waste percent, no kerf, no moisture shrinkage, no grade, and no sales tax. Plywood, dowels sold by the foot, and logs sold by another rule are outside the formula. Negative dimensions multiply to a negative board-foot number, because the page does not reject them. Cost at or above half a dollar rounds up to the next dollar. Below half a dollar it rounds down. $168.75 displays as $169.

FAQ

Is a board foot the same as a square foot?

No. A board foot is a volume: thickness in inches times width in inches times length in feet, divided by 12. A square foot is an area and does not divide by 12. Plywood is an area question.

Do I type nominal inches or the inches I measured?

Type the inches the seller is charging for. A nominal 2 by 4 by 8 displays as 5.33 board feet. The same length at 1.5 by 3.5 displays as 3.5 board feet. The form will not convert one into the other.

What if my length is in inches?

Divide by 12 and type feet. The page always divides by 12. It does not divide by 144. A 1 by 12 inch board that is 36 inches long is 3 feet, and the result is 3 board feet, not 36.

Why is the cost $187 when 53.33 times $3.50 looks like $186.66?

The displayed 53.33 is already rounded. The cost multiplies the unrounded total, 53.333… board feet, by 3.50, which is 186.666…, and then rounds to the nearest dollar, $187.

How much extra should I buy for waste?

The page does not add any. There is no waste field and no built-in percent. If you want more pieces, type the larger count. The sod calculator's 5 percent does not apply here.

What does a blank price mean?

Cost displays as N/A. A price of 0 displays as $0. Tax and delivery are never included, even when a price is filled in.

Why did 0 pieces still return a board-foot total?

A count that is empty or 0 is replaced with 1 before the multiply. The total you see is one piece. Reset clears the dimensions.

Related calculators

• Length Converter when the length is still in meters or inches
• Square Footage Calculator for sheet goods
• Paint Coverage Calculator
• Concrete Volume Calculator
• Sod Calculator which does apply a fixed 5 percent waste factor
• How to read a paint label