Add up the linear feet of boards, trim, fencing or any material sold by length. You can also convert square feet to linear feet for boards of a set width, and add a price per linear foot.
Extra for waste and cost
What is a linear foot?
A linear foot is simply 12 inches of length, measured in a straight line. Width and thickness don’t matter. A 10 ft board is 10 linear feet whether it’s 4 inches or 12 inches wide. That’s different from a square foot, which measures area, and a board foot, which measures volume of lumber.
Three ways to use the calculator
- Add up pieces: enter how many pieces you have and how long each is, in feet and inches. Add a row for each different length.
- Square feet to linear feet: enter the area you need to cover and the width of the board. Useful for decking, siding, flooring strips and shiplap.
- Linear feet to square feet: enter a length and width to see the area it will cover.
Linear foot formulas
- Linear feet = number of pieces × length of each (ft)
- Linear feet = total inches ÷ 12
- Linear feet from square feet = square feet × 12 ÷ board width (in)
- Square feet from linear feet = linear feet × board width (in) ÷ 12
Worked examples
- Mixed lumber: 10 boards at 8 ft plus 4 boards at 12 ft = 80 + 48 = 128 linear feet.
- Deck boards: to cover 200 square feet with boards 5.5 inches wide, you need 200 × 12 ÷ 5.5 = about 436 linear feet.
- Coverage: 100 linear feet of 5.5 inch boards covers 100 × 5.5 ÷ 12 = about 46 square feet.
Use the actual width of the board, not its name. A “6 inch” deck board is usually about 5.5 inches wide.
Where linear feet are used
- Fencing: measure the full fence line and take away gates.
- Trim and baseboard: measure each wall and leave out doorways.
- Lumber and decking: many yards price boards per linear foot.
- Rebar and pipe: sold in set lengths, so the total length tells you how many pieces to buy. The rebar calculator does this for slabs.
Price per linear foot
Open “Extra for waste and cost” and enter the price per linear foot. Add 5 to 10 percent extra for cuts and offcuts, since boards rarely divide evenly into the lengths you need.
Frequently asked questions
How do I calculate linear feet?
Measure the length of each piece in feet and add them together. If you measured in inches, add up the inches and divide by 12.
How many linear feet are in a square foot?
It depends on the width. With boards 6 inches wide, 2 linear feet cover 1 square foot. With boards 12 inches wide, it’s 1 linear foot.
Is a linear foot the same as a foot?
Yes. A linear foot is 12 inches of length. The word “linear” just makes clear it’s a length, not an area or volume.
How do I convert square feet to linear feet?
Multiply the square feet by 12 and divide by the width of the board in inches.
How many linear feet of fence do I need?
Measure every side of the area you’re fencing, add them together, and subtract the width of any gates.
Results are exact for the measurements you enter. See How We Calculate for the formulas we use.