Square Footage Calculator

Linear Feet to Square Feet

Linear feet cannot become square feet on their own — you need a width. Here is the calculation, and why materials are priced this way.

300sq ft

Formula: square feet = linear feet × width in feet

There is no conversion factor here, and any tool that offers you one is guessing. A linear foot measures length along a single line. A square foot measures area, which needs two dimensions. To get from one to the other you have to supply the missing one:

square feet = linear feet × width in feet

A 100-foot run of material 3 feet wide covers 300 sq ft. The same 100 linear feet at 6 inches wide covers 50.

Why so much material is sold this way

Anything that comes off a roll or out of a mill at a fixed width gets priced by length, because the width is not a variable the buyer chooses. Baseboard, crown molding, quarter-round, fencing, guttering, countertop and carpet runners are all quoted per linear foot for exactly that reason. The supplier already knows the width; you are only buying more or less of it.

The gap between the two units is where estimating errors live. Flooring is the usual culprit: planks are sold by the square foot but installed along a run, so a quote in linear feet and a floor measured in square feet need the plank width before they can be compared.

Converting the other way

If you know the area and the width, divide: 300 sq ft of 3-foot material is 100 linear feet. That is the calculation to run when a supplier quotes coverage and you need to know how much of the roll to ask for.

Linear feet to square feet table

Linear feet alone cannot become square feet. This table assumes a width of 3 feet; change the width above for your own run.

Linear feetSquare feet
10 linear ft30 sq ft
20 linear ft60 sq ft
30 linear ft90 sq ft
40 linear ft120 sq ft
50 linear ft150 sq ft
75 linear ft225 sq ft
100 linear ft300 sq ft
150 linear ft450 sq ft
200 linear ft600 sq ft
250 linear ft750 sq ft
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Other conversions

Need the area first? The square footage calculator works it out from your measurements, and the shape calculators handle the rooms and lots that are not a plain rectangle.