Linear Feet Calculator
Add up lengths for boards, trim and fencing, find the linear feet of baseboard around a room, or convert between linear feet and square feet using the board width. Results show feet, metres, yards and stock pieces, with a waste allowance.
Linear feet calculator
How to use the linear feet calculator
- Choose a mode. Add up pieces, measure a room's perimeter for trim, convert linear feet to square feet, or convert square feet to linear feet.
- Enter your measurements. Type lengths in feet, or feet and inches such as 8' 6". For conversions, add the board or material width in inches (millimetres in metric).
- Set waste and stock length. Keep 10% for cuts, then choose the stock length you will buy to see how many pieces you need. Add a price per foot if you want a cost.
- Read the result. The headline shows linear feet. The list adds metres, yards, inches, stock pieces and the area if you are converting.
Linear feet formulas
Linear feet = sum of (length × quantity)
Room perimeter = 2 × (length + width) − doorway widths
Square feet = linear feet × width (in) ÷ 12
Linear feet = square feet × 12 ÷ width (in)
A linear foot is 12 inches, or exactly 0.3048 m. Converting between linear and square feet always needs a second dimension, the width. The calculator adds your waste allowance to the total before it counts stock pieces.
Worked examples
Adding pieces. Four boards 8 ft long and two 6 ft long: 4 × 8 + 2 × 6 = 44 ft. With 10% waste that is 48.4 linear feet, or 7 eight-foot pieces.
Baseboard. A room 14 ft × 12 ft has a perimeter of 2 × (14 + 12) = 52 ft. One 3 ft doorway leaves 49 ft. With 10% waste, 53.9 ft, which is 7 pieces of 8 ft.
Square feet to linear feet. 100 ft² of flooring in 5½ inch boards needs 100 × 12 ÷ 5.5 = 218.2 linear feet, or 240 ft with 10% waste.
Linear feet to square feet. 100 linear feet of 5½ inch material covers 45.83 ft².
Linear feet per 100 square feet
| Board width | Linear feet per 100 ft² |
|---|---|
| 3¼ in | 369.2 |
| 5 in | 240.0 |
| 7¼ in | 165.5 |
| 11¼ in (2×12) | 106.7 |
Narrower boards need more length for the same area. Use actual widths (a 1×6 board is 5½ inches wide), not nominal ones.
Features
- Four modes in one tool: pieces, room perimeter, linear to square feet, and the reverse.
- Feet-and-inches input and metric units.
- Stock-length piece count and optional cost per foot.
- Copy result, reset, and a printable report in five designs on A4 or Letter.
Where linear feet are used
Trim, moulding, fencing, gutters, pipe, cable, edging and lumber are sold by the linear foot. Flooring, siding and sheet goods are sold by the square foot, so converting both ways helps you compare prices. For an area on its own, use the square footage calculator; for lumber orders by size use the lumber calculator; and for flooring boxes the flooring calculator.
Frequently asked questions
How do you calculate linear feet?
Measure the length of each piece in feet and add them together. Four 8 ft boards are 4 × 8 = 32 linear feet. For inches, divide by 12, so 30 inches is 2.5 linear feet.
How many linear feet is 1 ft?
One linear foot is simply one foot of length, measured in a straight line. It is a length, not an area or volume.
How much is 3 linear feet?
Three linear feet is 3 ft, 36 inches or 0.914 m. If the material is 6 inches wide, three linear feet covers 1.5 square feet.
How many linear feet is a 12x12 room?
The perimeter of a 12 ft × 12 ft room is 48 linear feet. Subtract doorways, so with a 3 ft door you need 45 linear feet of baseboard.
How do I convert linear feet to square feet?
Multiply linear feet by the width in feet (width in inches ÷ 12). One hundred linear feet of a 5½ inch board covers 100 × 5.5 ÷ 12 = 45.8 square feet.
Is 10 linear feet the same as 10 ft?
Yes, 10 linear feet and 10 feet are the same length. "Linear" just stresses that you mean length along a line, as opposed to square or cubic feet.
What does linear feet mean in freight shipping?
Carriers sometimes charge by the length of trailer floor your shipment occupies. That is a different use of the term and is quoted by the carrier, not worked out from the item's size.
Related calculators
Square Footage Calculator
Area of rooms and L-shapes in sq ft, m² and sq yd, with cut-outs and waste.
Lumber Calculator
Board feet, pieces, studs, joists and cost for a lumber order.
Flooring Calculator
Boxes of laminate, vinyl or hardwood for a room.
Board Foot Calculator
Board feet, cubic metres and cost for lumber.
Sources and references
About this calculator
Written and maintained by Rashid Mehmood, founder of CalcTen. The formulas are unit-tested against hand-worked examples, and the content is reviewed whenever product sizes or guidance change. Last updated 14 November 2026. See our editorial policy.
Results are estimates for planning and ordering. Always check product labels, supplier advice and local building codes, and consult a qualified professional for structural work. Read the disclaimer.