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Part of: What Is a Takeoff in Construction? How to Do One From Plans
Square Feet vs Linear Feet: What's the Difference?
Square feet vs linear feet comes down to area vs length. Square feet (SF) measure a surface, length times width, like a floor or a wall. Linear feet (LF) measure one dimension only, like a run of baseboard or fence. You cannot convert one to the other unless you know the width of the material.
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Upload your full plan set. Get every length, area and count. Export the takeoff to Excel.
A floor plan drawing, not a photo of a room.
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What is the difference between square feet and linear feet?
A linear foot is 12 inches of length, measured along a line. A square foot is the area of a square with 1-foot sides, which NIST Handbook 44 puts at exactly 144 square inches. Linear feet answer "how long?" and square feet answer "how much surface?"
Both show up on nearly every construction takeoff. Getting them mixed up, such as pricing trim by the square foot, makes a bid wrong from the first line.
| Square feet (SF) | Linear feet (LF) | |
|---|---|---|
| Measures | Area (two dimensions) | Length (one dimension) |
| Formula | Length × width | Length only, totaled across runs |
| Written as | SF, sq ft, ft² | LF, lin ft |
| Plan source | Traced rooms and surfaces | Wall runs, perimeters, edges |
| Takeoff items | Flooring, drywall, paint, slabs, sod | Base, crown, casing, fence, curb, edging |
When do you use linear feet vs square feet?
Use square feet when the work covers a surface and linear feet when the work runs along a line with a fixed width or height. A floor gets covered, so flooring is SF. Baseboard runs along the bottom of the wall at one height, so it is LF.
A quick test: if doubling the width of the area would double the material, you need square feet. If only the length matters, you need linear feet. Other units, like square yards and cubic yards, are covered in construction units of measure.
How do you convert linear feet to square feet?
Multiply linear feet by the width (or height) in feet. Going the other way, divide square feet by the width in feet. Without a width there is no conversion, because a line has no area.
- Linear feet to square feet: LF × width in feet = SF
- Square feet to linear feet: SF ÷ width in feet = LF
- Inches to feet: divide by 12 (6 inches = 0.5 ft)
The most common case on a takeoff is wall area. Room perimeter in LF times ceiling height in feet gives gross wall area in SF. Step-by-step methods for measuring runs off a plan are in how to calculate linear feet.
Worked examples by trade
All of these use the same room: 12 ft by 14 ft with an 8 ft ceiling and one 3 ft door. Its perimeter is 2 × (12 + 14) = 52 LF and its floor area is 12 × 14 = 168 SF. The perimeter calculator does the first number for any shape.
Painting: LF in, SF out
Walls: 52 LF × 8 ft = 416 SF gross, before you take out the door and windows. Ceiling: 168 SF. Paint covers a surface, so the paint lines are in SF even though you started from a perimeter in LF. The wall square footage calculator handles openings.
Trim and baseboard: LF
Base runs around the room but not across the door: 52 minus 3 = 49 LF. Crown molding would be the full 52 LF, because it runs above the door.
Drywall: SF, then sheets
Walls plus ceiling: 416 + 168 = 584 SF. A 4 × 8 sheet covers 32 SF, so 584 ÷ 32 = 18.25, which rounds up to 19 sheets before waste and before subtracting openings. The drywall takeoff page shows the same math done per room from a plan.
Decking or plank flooring: SF to LF
Boards are sold by length, but you measure the deck in square feet. Say a board covers 5.5 inches of width (check the product you are buying). That is 5.5 ÷ 12 = 0.458 ft, so a 168 SF deck needs 168 ÷ 0.458 = about 367 LF of board, before gaps and waste.
Fencing: LF, sometimes SF
A 150 LF fence line is quoted in linear feet. If you are staining it, the stain is an area job: 150 LF × 6 ft tall = 900 SF per side.
How do you get both from a floor plan?
Trace each room once and you have both numbers: floor area in SF and perimeter in LF. Multiply the perimeter by ceiling height for wall area, and you have the inputs for flooring, paint, drywall and base from a single pass.
The screenshot above shows that table. MeasureFloorPlan reports floor area in SF, perimeter in LF, and gross wall and ceiling area per room once the scale is set, and the Distance tool totals linear feet across separate runs. Painters can see the setup on painting estimating software.
Measure Plans in Minutes
Upload your full plan set. Get every length, area and count. Export the takeoff to Excel.
A floor plan drawing, not a photo of a room.
$9 per plan. 100% money-back guarantee.
Frequently Asked Questions
Is a linear foot the same as a foot?
Yes. A linear foot is 12 inches of length. The word "linear" just makes it clear you are measuring along a line, not an area or a volume.
What is a "linear square foot"?
There is no such unit. People use the phrase when they mean square feet of a material that comes in a fixed width, like a roll or a board. Work out the area in square feet, then divide by the width in feet to get the length you need.
How many linear feet are in 100 square feet?
It depends on the width. For something 1 foot wide, 100 SF is 100 LF. For something 6 inches wide (0.5 ft), it is 200 LF. For something 2 feet wide, it is 50 LF. Divide the square feet by the width in feet.
Do I subtract doors when I measure baseboard?
Yes, base does not run across a door opening. Take the room perimeter in linear feet and subtract the width of each door opening. Windows usually do not affect base because they sit above the floor.
How do I compare a price per linear foot with a price per square foot?
Divide the per-linear-foot price by the width in feet. Board that is $3 per LF and 6 inches (0.5 ft) wide works out to $3 ÷ 0.5 = $6 per SF. Without the width, the two prices cannot be compared.