How to Calculate Linear Feet – Step-by-Step Guide with Examples

Whether you’re ordering materials for a home renovation, estimating freight costs for a move, or planning a DIY project, knowing how to calculate linear feet is a fundamental skill. An accurate measurement can be the difference between a project that stays on budget and one filled with costly surprises. This comprehensive guide will walk you through exactly how to calculate linear feet for various scenarios, from a simple wall to an entire house.

What is Linear Feet?

A linear foot is a straightforward measurement of length that equals exactly 12 inches, or one foot. The term “linear” simply means “in a straight line.” This is the key differentiator from other units of measure.

• Linear Feet vs. Square Feet: Linear feet measure length alone. Square feet measure area, which is length multiplied by width. For example, a 10-foot long board is 10 linear feet. If that board is 1 foot wide, it covers 10 square feet of area.
• Common Uses: You’ll use linear feet when measuring walls for trim or siding, calculating the amount of fencing or lumber needed, determining flooring for a specific path, and estimating space for freight in a truck or shipping container.

How to Calculate Linear Feet of a Wall

Calculating the linear feet of a wall typically refers to finding its total length. However, in projects like installing baseboards or crown molding, you need the total perimeter of the room.

Steps to Calculate:

1. Measure the Length: Use a tape measure to find the length of each wall in feet and inches.
2. Calculate the Perimeter: For molding, trim, or fencing a room, add the lengths of all walls together.
3. Convert Inches to Feet: Ensure all measurements are in feet by converting any inches (e.g., 6 inches = 0.5 feet).

Example for a 12×12 Room:
A 12×12 room has four walls, each 12 feet long.
Linear Feet = 12 + 12 + 12 + 12 = 48 linear feet.
This means you would need 48 linear feet of baseboard to go around the entire room.

How to Calculate Linear Feet of a Rectangle or House

The process for a rectangle, a house foundation, or a fencing project is identical: you are calculating the perimeter.

Formula for a Rectangle:
Linear Feet = 2 × (Length + Width)

Application Example:
Imagine you are installing a fence around a rectangular yard that is 30 feet long and 20 feet wide.

1. Length + Width: 30 ft + 20 ft = 50 ft
2. Multiply by 2: 2 × 50 ft = 100 linear feet.
   You would need 100 linear feet of fencing material.

For a house, you would walk around the foundation, measuring the length of each exterior wall, and then sum them all to get the total linear footage for siding or gutters.

How to Calculate Linear Feet in Inches

It’s very common to have measurements in both feet and inches. Converting them is simple.

Conversion Formula:
Linear Feet = Total Inches ÷ 12

Example:
You have a wall segment that is 8 feet and 6 inches long.

1. Convert to Inches Only: (8 ft × 12) + 6 in = 96 + 6 = 102 inches.
2. Divide by 12: 102 ÷ 12 = 8.5 linear feet.

Always convert your measurements to feet before adding them together for a total to ensure accuracy.

How to Calculate Linear Feet of Flooring

Linear feet is used for flooring when the product comes in rolls or planks of a fixed width (e.g., vinyl rolls, certain types of hardwood sold in linear lengths).

Key Difference: You need to know the width of the material. If you are covering a full room, you would typically calculate square footage (Length × Width of the room). Linear footage is practical when you need a specific length, like for a hallway.

Example:
Your hallway is 10 feet long. You are buying vinyl plank flooring that comes in boxes where each plank is 6 inches wide.

• You need to cover the length of the hallway, which is 10 linear feet.
• The number of rows of planks you need depends on the width of the hallway and the plank, which is a separate calculation.

How to Calculate Linear Feet for Freight

In shipping and trucking, costs are often based on the linear feet of trailer space your freight occupies. This is calculated by measuring the length of your pallets or cargo items placed in a row.

Steps to Calculate:

1. Measure the length of each pallet or item in the direction it will be loaded into the truck.
2. Convert all measurements to feet.
3. Add the lengths of all items together.

Example:
You are shipping three pallets. Their lengths are 4 feet, 3.5 feet, and 5 feet.
Total Linear Feet = 4 + 3.5 + 5 = 12.5 linear feet.
This tells the freight company how much continuous truck space your shipment will require.

Step-by-Step Formula Summary

1. Collect Measurements: Measure the length(s) you need in feet and inches.
2. Convert to Feet: Use the formula: Feet = Inches ÷ 12.
3. Sum the Lengths: Add all individual lengths to get the total.

Quick Formulas:

• For a Single Length: Length (ft) = Feet + (Inches ÷ 12)
• For a Perimeter: Linear Feet = 2 × (Length + Width)
• For Multiple Items: Total Linear Feet = Item 1 Length + Item 2 Length + Item 3 Length…

Common Mistakes and Tips

• Mistake #1: Confusing Linear and Square Feet. Remember, linear is a line; square is an area. You cannot convert between them without knowing the width.
• Mistake #2: Not Converting Inches. Always convert inches to a decimal of a foot (e.g., 9 inches = 0.75 ft) before adding.
• Tip #1: Measure Twice, Calculate Once. Accuracy in the initial measurement is crucial.
• Tip #2: Account for Irregularities. For walls with juts or fixed cabinets, break the wall into smaller segments, measure each, and then sum them.
• Tip #3: Add for Waste. For projects like trim or fencing, add 5-10% to your total linear footage to account for cuts and mistakes.

Conclusion

Mastering the simple skill of calculating linear feet empowers you to tackle construction, moving, and DIY projects with confidence and precision. From ensuring you order the correct amount of materials to getting accurate freight quotes, this knowledge saves both time and money. Bookmark this guide and use it as your go-to reference for all your linear feet calculation needs.