How to Calculate Linear Feet
Linear feet is one of the most common measurements in building and home projects, yet it confuses a lot of people. Whether you are buying lumber, flooring, trim, or fencing, materials are often sold by the linear foot. Learning how to calculate linear feet is simple, and knowing the difference between linear feet and square feet will save you from costly ordering mistakes.
This guide explains what linear feet are, how to calculate them two different ways, and where the measurement is used.
What Are Linear Feet?
A linear foot is exactly what it sounds like: one foot of length, measured in a straight line. The key point is that linear feet measure length only — width and thickness do not matter. A 12-inch-wide board and a 6-inch-wide board that are both eight feet long are each eight linear feet.
This is why linear feet are used for materials that come in lengths, like planks, pipes, fencing, and trim. You are buying a certain total length, regardless of how wide each piece is.
Linear Feet Versus Square Feet
The most important distinction to understand is the difference between linear feet and square feet:
- Linear feet measure length in one direction only.
- Square feet measure area, which is length multiplied by width.
Confusing the two leads to ordering the wrong amount of material. If a project calls for linear feet and you calculate square feet, your numbers will be completely off. Always check which unit your material is sold in before you measure.
Method One: Adding Up Lengths
The simplest way to calculate linear feet is to add up the lengths of all your pieces. If you have ten boards that are each eight feet long, your total is 10 × 8 = 80 linear feet.
If your measurements are in inches, divide by 12 first to convert them to feet, then add them up. This method works any time you know how many pieces you have and how long each one is.
Method Two: Converting Area to Linear Feet
Sometimes you know the area you need to cover and the width of your boards, and you want the linear feet to order. This is common with flooring and decking. The formula is:
- Linear feet = area in square feet ÷ board width in feet
For example, to cover 120 square feet with boards that are 6 inches (0.5 feet) wide: 120 ÷ 0.5 = 240 linear feet. Because the board width is in inches, convert it to feet first, then divide. A linear feet calculator does both of these methods for you, so you never have to remember which conversion to apply.
Where Linear Feet Are Used
Linear feet show up across many materials and trades:
- Lumber and trim, sold by length
- Flooring and decking, where you convert area to linear feet of boards
- Fencing, measured along its run
- Countertops and molding, priced per linear foot
In each case, you are paying for a total length, which is why getting the linear-foot number right matters for your budget. It also helps to remember that prices are often quoted per linear foot, so once you know your total length you can multiply straight away to estimate the cost. Measuring carefully and adding a small allowance for cuts and offcuts means you order the right amount the first time, without a second trip to the supplier or a pile of leftover material you cannot use.
The Fast Way
Both methods are easy, but the area-to-linear conversion is where mistakes creep in. The reliable approach is a linear feet calculator: choose whether you are adding up pieces or converting from an area, enter your numbers, and it returns the total linear feet instantly.
Frequently Asked Questions
How do I calculate linear feet?
Add up the lengths of all your pieces in feet. If you only know the area and board width, divide the square footage by the board width in feet.
What is the difference between linear feet and square feet?
Linear feet measure length only, while square feet measure area, which is length times width. Materials sold by length use linear feet.
How do I convert square feet to linear feet?
Divide the area in square feet by the width of your board in feet. For a 6-inch board, that width is 0.5 feet.
Does board width affect linear feet?
No. Linear feet measure length only, so two boards of the same length are equal in linear feet no matter how wide they are.
Calculate Your Linear Feet Now
Once you know whether you are measuring length or area, the math is quick, and a tool removes any conversion errors. Open the linear feet calculator to get your total in seconds. Working on a bigger build? The concrete calculator and plywood calculator handle those materials just as easily.