What Is A Linear Foot? The Simplest Construction Measurement

Linear foot is a term that is crucial to learn, especially when you work in construction. After all, when it comes to terms of measurements, it’s important to use the correct measurement to get the correct amount of materials for your project.

One of the easiest yet most important terms of measurement is the linear foot. This is used every day in construction and is the basic term of measurement used for linear areas and materials, hence the name.

What Is A Linear Foot?

What Is A Linear Foot

A linear foot is a measurement used in construction to determine how many certain construction materials you need. Calculating it is similar to calculating the surface area of a shape. There’s a reason this measurement is so important.

But in short, a linear foot is simply twelve inches that are in a straight line. Many construction materials are sold by linear foot. This includes boards and other oblong materials that depend on the length rather than the width. 

How To Calculate Linear Feet

How To Calculate Linear Feet

When it comes to calculating the linear feet of a room’s walls, you need to get that measuring tape out. Learning how to measure linear feet is quite easy. You simply measure the length of a wall. then, measure the length of the opposite wall in the same room. 

You can generally assume that each opposite wall is the same. Finally, you measure the other two walls. Length only, not height. Now, add all four lengths together. This number is the linear foot of the room.

This is completely different than square feet. For example, the square footage of a 10×10 room is 100. But the linear footage of a 10×10 room is forty because each wall is ten feet long. Make sure you don’t confuse the two. 

How To Calculate How Much Paint You Need With Linear Foot

How To Calculate How Much Paint You Need

To calculate how much paint you need for a wall, you don’t need to know linear footage. Instead, you need to know the square footage. Not of the room, because that would be the floor. You need to know the square footage of the walls.

When painting, you need to use square footage to figure up how much paint you need. But in order to do this, you need to find the linear measurement of each wall to calculate the square footage of each wall. 

Step 1: Measuring The Walls

Measure the length of one wall first. For a 10×10 room, this will be ten feet. This is a linear measurement. Then, you take that same wall and measure the height. This is another linear foot measurement. 

Take the two numbers, usually around 8ft for the height, and multiply them. So your starting number for one wall would be 8×10. That’s 80 sqft for one wall. Then, do the same for all four walls, adding the total together. 

Step 2: Measuring Windows And Doors

Now, this is a step that can be skipped but will save you a lot of money if you do it. You need to measure the windows and doors. For example, say you have a standard door that is 36 inches wide by 80 inches tall

Convert that number to feet, which is around 3×7. Do the same for windows. Let’s say you have two windows that are 3×5 for this example. Let’s use those three numbers to calculate our total in the next step.

Step 3: Calculating The Total

Finally, it’s time to do the math. We have four walls that are 80sqft. This is a total of 320. But, if you want to save money, you subtract the total of the windows and doors. In this case, we have three numbers to work with.

The door at 3×7 is 21. Then you have two windows that are 3×5. This is 15 each for a total of 30 for windows. The windows and doors together are 51. Take 51 away from 320 to get 269. This is the square footage of the walls.

Step 4: Calculating The Amount Of Paint

Most paint covers about 350 sq feet a gallon. But you want to make sure you do two coats in most cases. So this room needs two gallons of paint as one gallon will do one coat. You can also buy pints for cheaper. 

Pints will cover about 50 sq ft. Quarts will cover around 100 sq ft. So, let’s say you need to cover the 269 sqft twice. So that’s 538. Take 350 away from that for one gallon and get 188. A gallon will overdo that.

But two quarts will be almost perfect. That said, quarts often cost more per ounce than gallons. So buying two gallons can save you money as opposed to buying one gallon and two quarts. So compare prices before buying.

What Is Sold By Linear Foot? 

What Is Sold By Linear Foot

There are two general measurements used to sell materials. Square foot and linear foot. But another important measurement is the cubic foot, which measures the length, width, and height, rather than just one or two measurements.

That’s a good way to remember which one is which. Linear is one measurement, the square is two measurements, and cubic is three measurements. This is a consistent way to keep them straight in your mind. 

Sold By Square Foot

Square foot covers a surface area and is the most common type of measurement used in construction. It is two measurements, length times width. Here are a few things that are measured by square feet. 

  • Flooringflooring is usually sold by the box, but in general, it will show how much square footage it covers because you need to cover the entire floor, not just the perimeter. This is true for any type of floor.
  • Paint – no matter what you’re painting, you will almost always calculate the square foot rather than the linear foot. This is because you need to cover a surface area. Even if it’s furniture, which is difficult to calculate.
  • Siding – siding, paneling, shiplap. Anything that is covering walls needs to be figured in square footage. You can figure how much you need in the same way that we figured how much paint for a room.

Sold By Linear Foot

Linear foot measures length only and is the simples form of measurement used in construction. It is one measurement, which is just length. Here are a few things measured by linear foot.

  • Cabinets – you may think that cabinets need to be measured by the square foot, and in some ways, they do. But they also need to be measured by linear foot because they go across the walls not in the center of the room.
  • Trim – trim goes around the edge of walls and doors. So it needs to be calculated by the linear foot. Measure the perimeter of a room, door, or window to figure the linear foot of the trim that you need.
  • Boards – boards are always measured by linear foot. The width and depth are also calculated, but the linear foot of the board is most dominant and how the boards are sold. When shopping, you ask for them in linear footage
  • Molding – molding is a lot like trim. It goes on the seam between the ceiling and the walls. It is measured just like trim and doesn’t have chunks taken out because windows and doors don’t reach the ceiling. 

Sold By Cubic Foot

Cubic feet is actually another word for volume. So if you learned that in school, you can figure cubic feet. It is length times width times height. Here are a few things sold by the cubic foot. 

  • Gravelgravel is usually sold by the load or cubic feet. This is because it is usually poured into ditches, gaps, and patios. So the easiest way to figure how much gravel you need is to measure the cubic feet.
  • Water – another thing that is poured is water. Water is almost always measured in cubic feet if in large amounts. There isn’t any other good way to calculate how much water is needed or present.
  • Stone – this is solid stone, as we already talked about gravel. Solid stone, marble, and other similar natural minerals are calculated in cubic feet because they are solid and surface area wouldn’t be useful knowledge.
  • Boxes – there it is! Of course, boxes and containers are calculated by cubic feet because you need to know how much they will hold. This is how moving vans and even shipping containers are calculated. 
  • Plasterplaster and even cement are usually calculated in cubic feet. Because sometimes, you need to cover a thin surface, and other times you need to put it on feet thick. So it needs to be calculated by the cubic foot. 

Do I Need To Learn All Of The Formulas?

Not generally. Although it can be useful to learn geometric formulas in life, there are a few tools that can eliminate the need to be able to carry them out manually. An application or browser tool can do wonders!

But so can hiring a professional who was trained to do this sort of math. In fact, some contractors choose the profession because they excelled in the subject in school! Geometry isn’t for everyone, but it is one useful tool!