Square Feet vs Linear Feet
Flooring is priced by the square foot. Crown molding is priced by the linear foot. Mix them up and you'll either under-order trim or over-order flooring by a lot. This guide explains the difference, when to use each, and how to convert between them reliably.
By Richard Taylor · Last updated:The Practical Problem
Imagine two different estimates arrive for your living room remodel:
- Flooring: $4.50 per sq ft for 180 sq ft = $810.
- Baseboard: $3.25 per linear ft for 54 lf = $175.50.
If you try to reason about the baseboard using square feet (or the flooring using linear feet) you'll get numbers that are either nonsensically low or way too high. Getting the unit right is the single most common source of material-ordering errors I see.
The Core Difference
| Square Feet (sq ft) | Linear Feet (lf) | |
|---|---|---|
| Dimensions | Two (length × width) | One (length only) |
| Measures | Area of a surface | Length of a piece |
| Formula | L × W | L |
| Used for | Flooring, tile, paint, carpet, roofing, real estate | Lumber, trim, molding, pipe, gutters, fencing, countertop |
| Abbreviations | sq ft, ft², sf | lf, ln ft, running ft |
Conversion Formulas
You can only convert between sq ft and lf if you know the width of the material:
| Going from | Formula | Example |
|---|---|---|
| Sq ft → Linear ft | lf = sq ft ÷ width (in ft) | 120 sq ft ÷ 0.5 ft = 240 lf of 6" plank |
| Linear ft → Sq ft | sq ft = lf × width (in ft) | 240 lf × 0.5 ft = 120 sq ft |
| Sq ft of a room → Linear ft of trim | perimeter = 2 × (L + W) | 12 ft × 10 ft room → 44 lf perimeter |
Worked Example 1: Hardwood Plank
A 180 sq ft bedroom is getting 5-inch-wide hardwood plank.
- Convert plank width to feet:
5 ÷ 12 = 0.4167 ft. - Divide:
180 ÷ 0.4167 ≈ 432 linear feetof plank. - Add 10% waste:
432 × 1.10 ≈ 475 lf. - Most boxes of 5-inch plank carry 22–24 sq ft per box, so you need
180 × 1.10 ÷ 23 ≈ 9 boxes.
Worked Example 2: Crown Molding
Same 180 sq ft room (say 12 ft × 15 ft). How much crown molding?
- Perimeter:
2 × (12 + 15) = 54 ft. - Add 10% waste for miter cuts:
54 × 1.10 ≈ 60 lf. - If molding comes in 8 ft sticks:
60 ÷ 8 = 7.5, round up to 8 sticks.
Notice: the sq ft of the room is irrelevant to the molding order. Only the perimeter (which is a linear measurement) matters.
Worked Example 3: Countertop
A kitchen countertop has a standard 25" depth, so only length varies.
- Measure total length of counter run: say
14 ft(a 10 ft main run + a 4 ft island). - Price quote:
$65 per linear foot. - Subtotal:
14 × 65 = $910, before edges and backsplash.
Sq Ft ↔ Linear Feet Calculator
Want to go back and forth for a specific plank width? Use the embedded calculator below — enter your room dimensions in feet, the calculator shows area, and the conversion table that follows lets you pick a plank width.
Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
Quick reference: square feet to linear feet by plank width
| Plank Width | Lf per Sq Ft | Lf in 120 sq ft | Lf in 300 sq ft |
|---|---|---|---|
| 3" | 4.00 | 480 lf | 1,200 lf |
| 5" | 2.40 | 288 lf | 720 lf |
| 6" | 2.00 | 240 lf | 600 lf |
| 7" | 1.71 | 206 lf | 514 lf |
| 8" | 1.50 | 180 lf | 450 lf |
| 12" | 1.00 | 120 lf | 300 lf |
When Each Unit Wins
Use square feet for
- Flooring — the calculator sums area regardless of plank width, then waste kicks in.
- Paint — coverage is spec'd per gallon at ~350 sq ft for one coat.
- Tile — coverage per box is advertised in sq ft.
- Carpet — often converted to sq yd (÷9) but still fundamentally area.
- Roofing — one "square" = 100 sq ft.
- Real estate — property listings report total sq ft per ANSI Z765.
Use linear feet for
- Baseboards, crown molding, quarter round — priced per lf; order the perimeter plus 10%.
- Dimensional lumber (2×4s, 2×6s) — priced per lf or per stick.
- Countertops — fixed depth, variable length.
- Gutters, downspouts — linear run along a roof edge.
- Chain-link fence, privacy fence — priced per lf of run.
- Plumbing / PEX / conduit — priced per lf.
Board feet — the weird sibling
For thick lumber, you'll see board feet: a volumetric measure defined as (thickness-in × width-in × length-ft) ÷ 12. A 2×4 that's 8 ft long is (2 × 4 × 8) ÷ 12 ≈ 5.33 board feet. Don't confuse this with linear feet — it's not the same thing.
Common Pitfalls
- Ordering flooring as linear feet. If a quote says "480 linear feet of 5" oak", divide by lf-per-sq-ft (2.4 for 5" planks) to sanity-check: 200 sq ft. Does that match your room? If not, something's wrong.
- Forgetting waste on trim. Miter cuts eat 4–6 inches per joint. Even a simple 4-corner room uses 10% more than the raw perimeter.
- Confusing "square" with "square foot". In roofing, one square = 100 sq ft. A quote for "25 squares" means 2,500 sq ft of shingle coverage.
- Assuming linear = perimeter. Trim usually matches perimeter, but stair nosing is just the count of steps × tread width — not the stair's perimeter.
Related Calculators & Guides
Flooring Calculator
Plank counts with waste built in.
⊞Main Calculator
Any shape, any unit.
$Cost per Sq Ft
Total price ↔ area-based budget.
▣Sq Ft vs Cubic Feet
Area vs volume for bulk materials.
✎Inches & Feet to Sq Ft
Convert mixed tape readings cleanly.
◈Price per Sq Ft
Understand cost math for any project.
Frequently Asked Questions
What is the difference between square feet and linear feet?
Square feet measure a two-dimensional area (length × width). Linear feet measure a one-dimensional length only. Flooring and paint use sq ft; trim, lumber, and countertops use lf.
How do I convert square feet to linear feet?
Divide the sq ft by the width of your material in feet. 120 sq ft ÷ 0.5 ft = 240 lf of 6" plank. Use the table above for common plank widths.
How many linear feet are in 120 square feet of flooring?
Depends on plank width. For 6 in planks it's 240 lf. For 5 in planks it's 288 lf. For 8 in planks it's 180 lf.
Is linear feet the same as running feet?
Yes. "Linear feet", "running feet", and "lineal feet" are interchangeable terms for straight-line length in feet.
Why is countertop sold by linear feet but tile by square feet?
Countertops have a standard depth (typically 25" for kitchens), so the only thing that varies is the length. Tile has no fixed size, so area is the right unit.
What is a board foot?
A board foot is a volume unit for lumber: (thickness-in × width-in × length-ft) ÷ 12. A 2×4 that's 8 ft long is about 5.33 board feet. Don't confuse board feet with linear feet.
Sources
- National Association of Home Builders — material pricing conventions (flooring, trim, countertops).
- ANSI Z765-2021 — square footage measurement standard.
- US NIST Handbook 44 — definitions of length and area units.