Ft to Linear Ft: Linear Feet vs Square Feet
Converting ft to linear ft is a 1:1 swap: one foot equals one linear foot. A linear foot is just a foot measured along a single direction, and the word "linear" is there to tell you that width and thickness are not part of the price. If a supplier quotes a price per linear foot, a 12-foot board costs twelve times that price no matter how wide the board is.
The conversion people are actually looking for is square feet to linear feet, and that one needs a width. The formula is: linear feet = square feet x 12 / material width in inches. So 200 square feet of 5-inch-wide flooring needs 200 x 12 / 5 = 480 linear feet of plank.
Need the area number first? Our free Square Footage Calculator gives you square feet for rooms, L-shapes, and odd angles, which is the input for every conversion on this page.
Updated September 2026
A note on numbers. This page gives you the conversions, the formulas and the units your quotes will use, not dollar figures. What a linear foot or a square foot costs is set by your suppliers, your region and the material you pick, and none of that is ours to publish. Get your quantities right here, then take them to local suppliers for pricing.
What a Linear Foot Actually Is
A linear foot is 12 inches of length. That is the entire definition. It is identical to a regular foot, and the only reason the trade uses a separate word is to signal what is being sold.
Think about what changes and what does not:
- A linear foot measures one dimension. Length only.
- A square foot measures two dimensions. Length x width, an area.
- A cubic foot measures three dimensions. Length x width x height, a volume.
- A board foot is a lumber-specific volume unit: 144 cubic inches, or a piece 1 inch thick by 12 inches wide by 12 inches long.
Suppliers price by linear foot when the width of the product is fixed and you cannot change it. A 2x6 is always a 2x6. A gutter profile is always that profile. A fence panel is always 6 feet tall. Since the cross-section never varies, the only variable is how much of it you buy, and that is length.
The moment the width can vary, linear feet stop working as a price unit. That is why hardwood in random widths is sold by the board foot, why flooring is sold by the square foot, and why countertops are sold by the linear foot only when a standard depth (usually 25 inches) is assumed.
How to Convert Ft to Linear Ft for a Materials List
Going from ft to linear ft when you already have a length is nothing: the number does not change. Measure 40 feet of wall and you need 40 linear feet of baseboard. What trips people up is the three real conversions on a materials list.
1. Square feet to linear feet (you have an area, you buy by length)
Linear feet = (square feet x 12) / material width in inches
Use this for flooring planks, siding boards, decking, and trim you are covering an area with.
2. Linear feet to square feet (you have a length, you need coverage)
Square feet = (linear feet x material width in inches) / 12
Use this to check whether the boards you already own will cover the room.
3. Linear feet to board feet (for rough hardwood)
Board feet = (thickness in inches x width in inches x length in feet) / 12
Use this at a hardwood dealer, where lumber is priced per board foot and comes in random widths. Our board foot calculator does this one for you including the quarter system, where 4/4 means one inch thick.
The one rule that prevents most mistakes: always use the actual coverage width, not the nominal width. A "6-inch" deck board is 5.5 inches wide. A "5-inch" flooring plank with a tongue and groove covers about 4.75 inches once installed. Using the nominal number under-orders your material by 5 to 10 percent, which is exactly enough to leave you one row short at the far wall.
Linear Feet vs Square Feet vs Board Feet at a Glance
| Unit | What it measures | Formula | Typically sold this way |
|---|---|---|---|
| Linear foot | Length only | Just the length | Trim, baseboard, crown, fencing, gutters, countertops, dimensional lumber, cable, pipe, curbing |
| Square foot | Area (L x W) | Length x width | Flooring, tile, drywall, roofing, carpet, sod, paint coverage, siding |
| Board foot | Lumber volume | (T x W x L in ft) / 12 | Rough and random-width hardwood, cabinet-grade stock |
| Cubic foot | Volume | L x W x H | Bagged mulch, soil, some aggregates |
| Cubic yard | Volume, 27 cu ft | (L x W x H in ft) / 27 | Concrete, gravel, mulch and topsoil in bulk |
| Square (roofing) | 100 square feet | Square feet / 100 | Shingles and roofing underlayment |
Two of those cause most of the confusion in quotes.
A "square" in roofing is 100 square feet. A roofer saying "22 squares" means 2,200 square feet of roof surface, not 22 square feet.
A linear foot of countertop assumes a depth. The industry standard is 25 inches of depth for a base cabinet run. If your island is 36 inches deep, a per-linear-foot price will not cover it, and the fabricator will either quote by the square foot or add a premium. Ask which one you are being quoted.
Square Feet to Linear Feet by Material Width
This is the table to bookmark. It shows how many linear feet you need to cover 100 square feet at each common coverage width, and it is the fastest way to sanity-check a supplier's quantity.
| Coverage width | Linear feet per 100 sq ft | Common products at this width |
|---|---|---|
| 2.25 in | 533 lf | Strip oak flooring |
| 3.25 in | 369 lf | Wide strip flooring, some engineered |
| 4.75 in (5 in nominal) | 253 lf | Plank flooring, luxury vinyl plank |
| 5.5 in (6 in nominal) | 218 lf | Deck boards, fence boards, T&G porch |
| 6.75 in (7.5 in nominal lap) | 178 lf | Lap siding at standard exposure |
| 7.25 in (8 in nominal) | 166 lf | Wide deck boards, shiplap |
| 11.25 in (12 in nominal) | 107 lf | 1x12 shelving, wide siding |
To use it, divide your square footage by 100 and multiply. A 340 square foot deck with 5.5-inch boards needs 3.4 x 218 = 741 linear feet of decking before waste. Add 10 percent for cuts and you are ordering about 815 linear feet, which at 16-foot boards means 51 boards.
Our deck calculator does that math and the joist and fastener counts, and the flooring calculator handles plank flooring with the waste factor built in.
Where Each Unit Shows Up in Real Quotes
Here is what your contractor is almost certainly quoting, by trade.
| Job | Priced by | What moves the per-unit price | Notes |
|---|---|---|---|
| Baseboard, installed | Linear foot | Profile width and height, material, number of inside and outside corners | Wider and taller profiles cost more |
| Crown molding, installed | Linear foot | Corner count, ceiling height, whether returns and coped joints are needed | Corners and returns drive labor |
| Kitchen countertop | Linear foot (25 in depth) | Material above all else, then edge profile, sink cutouts and seams | Laminate at the low end, quartz and granite mid, exotic stone high |
| Wood privacy fence, installed | Linear foot | Height, post depth and spacing, gates, slope of the run, rock in the holes | Height and post depth move it most |
| Chain link fence, installed | Linear foot | Mesh gauge, height, terminal post count | The cheapest fence type per foot |
| Vinyl fence, installed | Linear foot | Panel style and thickness, post reinforcement, height | Pricier per foot than wood, cheaper over its life |
| Gutters and downspouts | Linear foot | Material, story count, number of downspouts and inside corners | Seamless aluminum at the low end, copper far higher |
| Retaining wall block | Face square foot | Wall height, whether engineering and geogrid are required, drainage and backfill | Height matters, so area not length |
| Flooring, installed | Square foot | Material, subfloor prep, room shape and cut count | The material choice swamps everything else |
| Drywall, hung and finished | Square foot | Finish level, ceiling height, the number of corners and openings | Level 5 finish costs well above level 4 |
| Siding, installed | Square foot | Material, story count, staging, trim detail, whether the old siding comes off | |
| Roofing | Square (100 sq ft) | Pitch, layer count, tear-off, decking repairs, penetrations and valleys | Asphalt shingle, average pitch |
| Trenching for utilities | Linear foot | Soil type, depth, rock, access for the machine, restoration afterward | Soil and depth drive it |
| Concrete curbing | Linear foot | Curve count, mix, finish, whether forms are needed |
Notice the pattern. Anything long and thin is priced by the linear foot. Anything that covers a surface is priced by the square foot. A retaining wall is the interesting exception: it is long and thin in plan, but its cost scales with height, so it gets priced by face area instead. Our cost to build a fence page walks through why fencing keeps a per-linear-foot price even though height changes the material list.
Worked Example 1: Baseboard for a Whole Floor
A homeowner is replacing baseboard on a main floor with four rooms and a hallway.
Measure the perimeter of each room, then subtract door openings.
| Room | Dimensions | Perimeter | Door openings to subtract | Net linear feet |
|---|---|---|---|---|
| Living room | 14 ft x 18 ft | 64 ft | 2 openings at 5 ft | 54 lf |
| Dining room | 12 ft x 14 ft | 52 ft | 1 cased opening at 6 ft | 46 lf |
| Bedroom 1 | 12 ft x 12 ft | 48 ft | 1 door at 3 ft, 1 closet at 5 ft | 40 lf |
| Bedroom 2 | 11 ft x 12 ft | 46 ft | 1 door at 3 ft, 1 closet at 4 ft | 39 lf |
| Hallway | 4 ft x 22 ft, one side open | 44 ft | 3 doors at 3 ft | 35 lf |
| Total | 214 linear feet |
Add waste. Baseboard runs get cut at corners and at scarf joints, and you cannot use every offcut. Add 10 percent on straight rooms and 15 percent if there are many short walls or angles. At 12 percent: 214 x 1.12 = 240 linear feet.
Convert to sticks. Baseboard comes in 16-foot lengths at most lumberyards. 240 / 16 = 15 pieces. Buy 16, because one bad piece in the bundle is normal.
Cost it out.
| Line | Quantity | Share of the bill |
|---|---|---|
| Primed MDF base, 5.25 in, 16 ft sticks | 16 sticks | The dominant line, and it scales directly with the profile you pick |
| Finish nails, adhesive, caulk, wood filler | 1 lot | Minor, but do not skip the filler and caulk, they are what makes it look installed |
| Paint, 1 gallon trim enamel | 1 gallon | Modest, and one gallon covers this whole run |
| DIY materials | 240 lf purchased | A one-trip material bill |
| Installed by a carpenter | 214 lf billed | Several times the material bill, because trim is almost entirely labor |
Note what happened there. You order by the 240 linear feet you buy, but you get billed by the 214 linear feet you install. Contractors quote installed length, not purchased length, and the waste is inside their price. Comparing your material number to their labor number without noticing that gap is a common budgeting error.
To turn this into a real number, take your net installed linear feet to three carpenters, tell each one the exact profile and material, and ask for a price per installed linear foot with paint listed separately. Those three quotes are comparable. A quote that omits the profile is not.
Worked Example 2: A Deck, Where Both Units Appear
A 16 ft x 20 ft deck shows why you need both units in the same project.
Square feet, for the surface: 16 x 20 = 320 square feet. That is the number for the permit application, for the composite decking price per square foot, and for the stain coverage later.
Linear feet, for the boards: using 5.5-inch actual-width boards laid across the 16-foot direction:
- Rows needed: 20 ft x 12 in = 240 inches of run, divided by 5.75 inches per row (5.5-inch board plus a 0.25-inch gap) = 42 rows
- Each row is 16 feet long, so 42 x 16 = 672 linear feet of decking
- Add 10 percent for cuts and defects: 740 linear feet
- At 16-foot boards with no waste per row: 42 boards, buy 46
Linear feet, for the framing: the rim joists are 2 x 20 ft plus 2 x 16 ft = 72 linear feet. Joists at 16 inches on center across 20 feet: 16 joists at 16 ft each = 256 linear feet. Beam, blocking, and ledger add about 90 linear feet. Total framing lumber: 418 linear feet.
Linear feet, for the railing: 16 + 20 + 16 = 52 linear feet of railing on three sides, since the fourth is the house.
Square feet again, for the stain: 320 square feet of deck surface plus roughly 60 square feet of railing faces. At 200 square feet per gallon on rough wood, that is 2 gallons per coat.
One deck, five different numbers, and every one of them is correct for its own line item. That is the whole point of keeping the units straight. Our how to build a deck guide walks through the framing side in order.
Waste Factors Worth Building In
Ordering exactly what the math says is how projects stall. Here are the working allowances.
| Material | Add for waste | Why |
|---|---|---|
| Baseboard and casing, straight rooms | 10% | Corner cuts and unusable offcuts |
| Trim in rooms with angles or many short walls | 15% | More cuts per foot |
| Decking, straight lay | 10% | End cuts and rejected boards |
| Decking, diagonal lay | 15 - 20% | Every board gets angle cuts on both ends |
| Flooring, plank, straight lay | 8 - 10% | Racking and starter rows |
| Flooring, herringbone or diagonal | 15 - 20% | Heavy cutting |
| Siding, lap | 10 - 15% | Openings and corner waste |
| Fence pickets | 5 - 10% | Culls in the bundle |
| Countertop | 10% on stone slabs | Seams and edge fabrication |
There is a second reason to over-order that nobody mentions until it bites: dye lots and mill runs. Boards from a different production run can be a slightly different color or thickness. If you come up short three months later, matching is often impossible. Buying 10 percent extra at the start is cheap insurance and leaves you spare pieces for repairs.
Common Mistakes That Cost Money
Using nominal width instead of actual width. A 2x6 is 1.5 x 5.5 inches. A 1x8 is 0.75 x 7.25 inches. Every dimensional lumber size is smaller than its name.
Forgetting the gap. Deck boards get a 1/8 to 1/4 inch gap between them. Over 42 rows, a 1/4 inch gap consumes about 10 inches of run, which is two extra rows on a big deck.
Ignoring the exposure on lap siding. A 8-inch lap board only exposes about 6.75 inches after the overlap. Ordering by the board width rather than the exposure under-orders siding badly. Our siding cost page uses exposure-based coverage for exactly this reason.
Assuming a linear foot price includes everything. A per linear foot fence quote may or may not include gates, post setting depth, hauling the old fence away, and permits. Get the inclusions in writing.
Mixing the units in one quote comparison. If one contractor quotes per linear foot and another quotes per square foot, convert both to a total for your actual job before you compare. Percentages and per-unit prices hide too much.
Frequently Asked Questions
Is a linear foot the same as a foot?
Yes. A linear foot is exactly one foot of length, 12 inches. Converting ft to linear ft is a 1:1 swap with no math involved. The word "linear" only tells you that you are measuring in one direction, and that width and thickness are not part of what you are being charged for.
How do you convert square feet to linear feet?
Multiply the square footage by 12, then divide by the material's coverage width in inches. So 250 square feet of 5.5-inch decking is 250 x 12 / 5.5 = 545 linear feet. Always use the actual coverage width, not the nominal size, because a 6-inch board is really 5.5 inches wide.
How do you calculate linear feet for a fence?
Measure the perimeter you want to enclose, in feet, following the actual fence line. That total is your linear footage. Do not subtract gates from the number, because gate hardware and posts usually cost more per foot than fence, not less. For a rectangular yard, linear feet = 2 x (length + width) minus any side you are not fencing.
What is the difference between a linear foot and a board foot?
A linear foot measures length only. A board foot is a volume: 144 cubic inches, calculated as thickness x width x length in feet, divided by 12. Dimensional lumber at a home center is priced by the linear foot because the sizes are fixed. Hardwood at a lumber dealer is priced by the board foot because widths are random.
How many linear feet are in a square foot?
There is no fixed answer without a width. One square foot of 12-inch-wide material is 1 linear foot. One square foot of 6-inch-wide material is 2 linear feet. One square foot of 3-inch-wide material is 4 linear feet. The narrower the material, the more length it takes to cover the same area.
Why are countertops priced per linear foot?
Because base cabinets are a standard 24 inches deep, so a countertop run is a standard 25 to 26 inches deep with the overhang. That fixed depth lets fabricators quote by length. When the depth changes, such as on a wide island or a bar overhang, the price shifts to a square foot basis or the fabricator adds a premium. Ask which basis your quote uses before comparing bids.
How many linear feet of flooring do I need for a 12x15 room?
The room is 180 square feet. At 4.75-inch coverage width, that is 180 x 12 / 4.75 = 455 linear feet. Add 10 percent for waste and order about 500 linear feet. Most flooring is sold by the square foot in cartons, so you would actually buy 198 square feet, which is 10 cartons at roughly 20 square feet each.
Do contractors quote linear feet installed or purchased?
Installed. A per-linear-foot quote covers the length that ends up on your wall, deck, or property line, and the contractor's waste allowance is built into their price. When you buy materials yourself, you buy the larger purchased number. Comparing your purchase quantity to their installed quantity makes a quote look worse than it is.
Related Reading
- Square Footage Calculator - the area number every conversion on this page starts from
- Board Foot Calculator - for hardwood priced by volume rather than length
- Deck Calculator - decking, joists, and fasteners from your deck dimensions
- Cost to Build a Fence - the classic per-linear-foot quote, broken apart
- Siding Cost - why exposure, not board width, sets your material order
