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Part of: What Is a Takeoff in Construction? How to Do One From Plans

How to Calculate Linear Feet (With Examples From Plans)

To calculate linear feet, measure the length of each run in inches, divide by 12, and add the runs together. Width and thickness do not matter, only length. If you start from square feet instead, divide the area by the width of the material in feet. Both methods come up in almost every construction takeoff, from baseboard and crown to fence lines and wall plates.

What is a linear foot?

A linear foot is one foot of length, measured in a straight line, with no regard for width or thickness. A 10 foot piece of 1x4 trim and a 10 foot 2x12 are both 10 linear feet. Estimators write it as LF.

Linear feet is the unit for anything you buy or install by the run. If you are not sure whether an item is priced by length or by area, start with the difference between square feet and linear feet.

How do you calculate linear feet?

Measure each piece or run, convert it to feet, and add them up. Inches divided by 12 gives feet. A wall that is 14 feet 6 inches long is 14 + (6 ÷ 12) = 14.5 linear feet. Three runs of 14.5, 12 and 9.25 feet add up to 35.75 LF.

1. Measure every run you need, end to end.
2. Convert inches to decimal feet by dividing the inches by 12.
3. Add all the runs for a total.
4. Round up to the lengths the material is sold in, then add waste.

How do you convert square feet to linear feet?

Divide the square footage by the width of the material in feet. The formula is linear feet = square feet ÷ width in feet. You cannot convert without a width, because a narrow board needs far more length than a wide one to cover the same area.

Use the actual width, not the name of the board. Lumber is sold by nominal size, and the finished dimensions are smaller than the nominal ones. A 1x6 is actually 3/4 inch by 5 1/2 inches. For tongue and groove or shiplap, use the covering face width the supplier lists, since part of each board hides in the joint.

The math behind the table is 12 divided by the width in inches. For a 1x6, 12 ÷ 5.5 = 2.18 linear feet for every square foot. A 120 square foot wall in butt-joined 1x6 takes 120 × 2.18 = about 262 LF before waste.

Carpet works the same way off the roll. Shaw notes that most carpet is made in 12 foot rolls, with 15 foot rolls also available. A 12 by 20 foot room is 240 square feet, and off a 12 foot roll that is 240 ÷ 12 = 20 linear feet of carpet. Wider rooms need seams, which add material.

How do you get linear feet from a floor plan?

Set the plan scale, then measure each run along the walls or lines you need and total them. For baseboard, take the room perimeter and subtract the door openings. That is the same method Pergo's flooring project planner gives for wall base and quarter round.

1. Check the scale against a printed dimension. If you are not sure how, read up on how to scale a floor plan first.
2. Find the room length and width from the dimension strings.
3. Add length and width, then multiply by 2 for the perimeter.
4. Add up the widths of every doorway in the room.
5. Subtract the doorway total from the perimeter to get linear feet of base.

Worked example: a bedroom is 12'-0" by 14'-6" with one 3'-0" door. The perimeter is (12 + 14.5) × 2 = 53 LF. Take off the 3 foot door and you need 50 LF of baseboard. For odd-shaped rooms, add each wall segment instead, or check your numbers with a perimeter calculator.

Read the dimension strings, not your ruler, wherever they exist. Some walls are dimensioned to the face of stud and some to the centerline, and reading blueprint dimensions correctly keeps a few inches per wall from adding up across a house.

On a PDF, you can click each run instead of adding by hand. MeasureFloorPlan's Distance tool totals linear feet across runs once the scale is set from one dimensioned wall, which helps on long trim and takeoffs for contractors who bid from the plan.

Which trades measure in linear feet?

Most trades have at least one line item in LF. Here is where the run comes from on a typical plan set.

How much extra should you add to linear feet?

Add waste after you have the net run, not before. Trim loses length at every miter and coped joint, and leftover short pieces are hard to reuse on long walls. The right allowance depends on the material and how many corners the job has.

Published figures vary by product, so check the manufacturer before you pick a number. Sourced allowances by material are collected in construction waste factors by trade.

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