What is a linear foot?

A linear foot is simply one foot of length measured in a straight line, ignoring width and depth. A 40 foot long footing is 40 linear feet whether it is 16 or 24 inches wide.

How do I convert square feet to linear feet?

You cannot convert directly without a width. Linear feet = square feet divided by the width in feet. 300 square feet of footing at 20 inches (1.667 feet) wide is 180 linear feet.

How do I add feet and inches without mistakes?

Convert inches to decimal feet before adding: divide inches by 12. So 24 feet 6 inches is 24.5 feet. Adding mixed feet-and-inches in your head is the single most common source of takeoff errors.

Is a linear foot the same as a foot?

Yes — "linear" just clarifies that you are measuring length only, as opposed to square feet (area) or cubic feet (volume).

How to Measure Linear Feet (of Footing)

The method

List every run. Outer perimeter first — each printed dimension between corners is one run. Then every interior foundation wall.
Convert inches to decimals. 24'-6″ → 24.5'. 13'-4″ → 13.33'. Never add feet-and-inches in your head.
Add them up. That's your linear feet.
Cross-check. On a closed plan, north-side segments must sum to the south side, east to west. If they don't, you missed a jog.

Worked example

Run	Plan dim	Decimal ft
Front wall	42'-0″	42.00
Right side	28'-6″	28.50
Rear wall	42'-0″	42.00
Left side	28'-6″	28.50
Beam-line wall	38'-8″	38.67
Total		179.67 LF

Do this interactively — with rates and pads — in the linear feet of footing calculator.

The two classic mistakes

Missed jogs. Every bump-out in the perimeter adds two short runs. They hide in dimension strings and cost 4–12 LF each.

Square feet confusion. Linear feet is not square feet. You can only go between them with a width: LF = ft² ÷ width(ft). Without the width, the "conversion" people search for doesn't exist.

How to Measure Linear Feet

The method

Worked example

The two classic mistakes

Doing whole plans, not single runs?

Linear feet, answered.