How to use the linear feet calculator
- Choose the conversion: linear feet to square feet, square feet to linear feet, linear feet to board feet, board feet to linear feet, or compare prices per unit.
- Enter the quantity and the board width. For board feet and prices, enter the thickness too. Pick inches, centimeters or millimeters for the width and thickness.
- Optionally enter a piece length such as 8 or 12 feet to turn the linear feet into a count of boards, with an extra percentage for waste.
- Read the converted value and the matching units. In price mode, enter the price per linear foot, per square foot or per board foot to see the other two.
Formula
Square feet = linear feet x width in inches / 12
Linear feet = square feet x 12 / width in inches
Board feet = linear feet x thickness in inches x width in inches / 12
Linear feet = board feet x 12 / (thickness x width)
Price per square foot = price per linear foot / (width / 12)
Price per board foot = price per linear foot / (thickness x width / 12)
Boards = linear feet x (1 + waste percent / 100) / piece length, rounded up
One linear foot of a board that is W inches wide covers W / 12 square feet, and holds T x W / 12 board feet when the thickness is T inches. Every conversion on this page uses that single relationship, so the results always agree with each other.
Worked example: 100 linear feet of a 5.5 inch wide board
A board 5.5 inches wide covers 5.5 / 12 = 0.4583 square foot for every linear foot. A hundred linear feet cover 100 x 5.5 / 12 = 45.83 sq ft, which is 4.258 square meters.
Going the other way, 100 sq ft needs 100 x 12 / 5.5 = 218.18 linear feet. In 12 foot boards that is 18.18, so 19 boards, or 20 boards with a 10% waste allowance.
At 1.5 inches thick, 100 linear feet is 100 x 1.5 x 5.5 / 12 = 68.75 board feet.
If a board costs $2.40 per linear foot, the same board costs $2.40 / 0.4583 = $5.2364 per square foot at 1 inch thick, and the same $5.2364 per board foot.
Linear, square and board feet
Lumber, trim and flooring are priced in three different units that all describe the same board. A linear foot measures only length. A square foot adds the width, so it tells you how much floor or wall the board covers. A board foot adds the thickness too and measures how much wood is in the piece. One board foot is a piece 1 foot long, 1 foot wide and 1 inch thick, or 144 cubic inches.
Which unit a seller uses depends on the product. Trim and molding are sold by the linear foot, flooring and decking by the square foot or the box, and hardwood lumber by the board foot. To compare two products, convert them all to the same unit, and the price mode here does it for you.
Actual size and nominal size
A board sold as a 1x6 is not 1 inch by 6 inches. Planing leaves it about 3/4 inch thick and 5.5 inches wide, and the other sizes follow the same pattern. Enter the actual width for the coverage and the size the seller bills by for the price. A hardwood seller may bill by a rough thickness in quarters of an inch, so confirm what the quote is based on before you compare.
If the board is a tongue and groove or has a milled edge, the face you see is narrower than the board is wide. Use the covered width, not the width of the whole board, when you want to know how much floor it covers.
Buying in whole pieces
Linear feet are rarely bought exactly. Boards come in set lengths such as 8, 10 and 12 feet, so the tool rounds up to whole pieces when you enter a piece length. Short leftover offcuts are only useful if they are long enough for another run, which is why the waste percentage is yours to set.
Assumptions and limits
- Every piece has the same width and thickness along its whole length. Tapered boards and profiles with a curved face are not modeled.
- Width and thickness are the actual sizes you enter. The tool does not convert nominal sizes.
- Board feet use the formula thickness x width x length / 12 with inches and feet. Hardwood grading and rough sizes are outside the scope.
- The waste percentage applies only to the board count, not to the area or volume.
- Prices are the numbers you enter. Tax, delivery and volume discounts are not included.
Frequently asked questions
How do I convert linear feet to square feet?
Multiply the linear feet by the width in inches, then divide by 12. A hundred linear feet of a 5.5 inch board covers about 45.83 square feet.
How many linear feet are in a square foot?
It depends on the width. A board 6 inches wide needs 2 linear feet to cover a square foot, and a 3 inch wide board needs 4. In general it is 12 divided by the width in inches.
How do I convert linear feet to board feet?
Multiply the linear feet by the thickness and the width in inches, then divide by 12. Linear feet of a 1 by 12 inch board are the same as board feet.
What is the difference between a linear foot and a lineal foot?
They mean the same thing, which is a foot of length measured along a board without regard to its width or thickness.
How do I compare lumber priced per linear foot and per board foot?
Convert both to the same unit with the actual width and thickness of each product. The price comparison mode turns one price into all three units.