Linear Feet Calculator
This free linear feet calculator gives you the running-foot total that trim, fencing, gutter, deck railing, and dimensional lumber are priced and ordered in. Pick a mode: rectangle perimeter for a baseboard run or a fenced yard, add-up-runs for a multi-sided fence or gutter layout, or square-feet-to-linear-feet for decking and plank flooring. Enter feet and inches, set how many of each run, and the calculator totals it.
Linear feet is a length, not an area or a volume — a 4-inch board and a 12-inch board of the same length are identical linear feet, which is exactly why material sold by the running foot is priced this way. Subtract openings where nothing runs (doorways for baseboard, gates for fence) — but leave crown molding undeducted, since it runs continuously over the doors. Add a stock length and the calculator rounds your running feet up to whole 8, 12, or 16-foot sticks.
Built on the foot as a unit of length (NIST Handbook 44) with a waste factor for miters and offcuts — no signup, no pricing. Once you have your linear feet, feed the number into the Trim, Fence, Gutters, Deck, or Retaining Wall calculator to finish the take-off with materials and fasteners.
Linear Feet Calculator
Work out linear feet (running feet) three ways — the perimeter of a rectangle, the sum of straight runs, or a square-foot area converted to board linear feet. Subtract door and gate openings, add a stock length to see how many sticks to buy, and apply a waste factor. The running-foot unit trim, fencing, gutters, and railing are priced in. Free, no signup.
Rectangle dimensions
Baseboard vs. crown — what do I subtract for doors? See the perimeter diagram
Openings to subtract (optional)
No openings — the full perimeter will be used.
Stock length & waste (optional)
What a linear foot really is
Linear feet trips people up because it isn't an area or a volume — it's pure length, the unit material sold by the running foot (trim, fence, gutter, pipe, railing) is priced in. These engineering-style diagrams show why width and thickness never count, how a room's perimeter feeds baseboard and crown with different opening deductions, and how to turn a square-foot coverage area into running feet of boards.
The length-only diagram is why the calculator counts running goods by length alone. A linear foot is twelve inches of length regardless of width or thickness, so a narrow trim board and a wide one of the same length are the same linear feet. Buy trim, fence, or gutter by the linear foot and coverage goods by the square foot — the diagram keeps the two units apart.
The perimeter diagram explains why the deduction depends on the trade. A rectangle’s perimeter is a fixed number, but baseboard skips the doorways while crown runs over them, so the same room gives two different linear-foot totals. That is why the calculator asks what the run is for before it deducts openings.
The area-to-length diagram is why board width changes the linear feet for the same floor. Coverage becomes running feet through the board’s face width, so narrower boards need more linear feet to cover the same area. Order decking or flooring by the linear foot without accounting for width and the count is off.
Calculation Formulas
A linear foot — also called a running foot — measures length only. Width and thickness do not enter, which is what separates it from square feet (area) and board feet (volume).
Example:
A 16-ft stick of baseboard is 16 linear feet whether it is 3 in or 7 in tall.
The running feet around the outside edge of a rectangle — the baseboard run of a room, the fence around a yard, or the railing around a deck.
Example:
A 14 × 12 ft room = 2 × (14 + 12) = 52 linear feet of perimeter.
Add up every straight run. Multiply repeated identical runs (two equal fence sides, four gutter eaves) by their count.
Example:
40 ft back fence + two 25 ft sides = 40 + (25 × 2) = 90 linear feet.
Convert a feet-and-inches measurement to decimal feet before adding runs together so partial lengths total correctly.
Example:
12 ft 8 in = 12 + 8 ÷ 12 = 12.67 linear feet.
Deduct doorways, gates, and gaps where no material runs. Baseboard stops at door casings; crown molding does NOT — it runs continuously over openings, so do not deduct for crown.
Example:
52 LF perimeter − a 3 ft doorway = 49 LF of baseboard.
Convert a coverage area to running feet of boards laid side by side. Each linear foot of board covers (face width + gap) ÷ 12 square feet, so dividing the area by that coverage gives the board linear feet.
Example:
200 sq ft of 5½ in decking at a 3⁄16 in gap = 200 × 12 ÷ 5.6875 = 422 linear feet.
Material is sold in fixed stock lengths (8, 12, 16 ft …). Divide the running feet you need by the stock length and round up to whole sticks.
Example:
90 LF of fence rail in 8-ft sticks = ⌈90 ÷ 8⌉ = 12 sticks.
Add a waste factor for offcuts, miters, and damage before buying. Miter-heavy trim wants more; long straight runs of fence or gutter want less.
Example:
49 LF of baseboard at 12% waste = 55 LF to buy.
Standard Constants
| Constant | Value | Description |
|---|---|---|
| 1 linear foot | 12 inches | The base unit of running length; width and thickness are irrelevant. |
| Rectangle perimeter | 2 × (L + W) | Running feet around a four-sided room, yard, or deck. |
| Trim / molding waste | 10–15% | Allowance for miter cuts, cope joints, and pattern matching. |
| Fence / gutter waste | 5–10% | Long straight runs waste little; corners and end cuts add some. |
| Decking board face width | 5½ in (nominal 6) | Actual coverage width of a standard 5/4×6 or composite deck board. |
| Decking gap | ⅛–3⁄16 in | Standard spacing between deck boards for drainage and expansion. |
| Common trim stock lengths | 8, 12, 14, 16 ft | Molding and dimensional lumber are sold in these running lengths. |
| Typical interior door opening | 32–36 in | Deduct the door width from baseboard run (not from crown). |
Note: All calculations include appropriate waste factors based on project complexity and material type. Results are estimates and should be verified by professionals before purchasing materials.
NIST Handbook 44 — Units of Length(NIST HB 44)
View StandardThe US authority for legal units of measure, including the foot and inch used for linear (running) measurement.
Key Requirements:
- •1 foot = 12 inches; 1 yard = 3 feet.
- •Linear measure is length only — independent of width or thickness.
- •Commercial material sold "by the linear foot" is priced on length.
WM/LWM Moulding Series (Trim Lengths)(WMMPA WM)
View StandardWood Moulding & Millwork Producers Association standard profile series, sold in standard running-foot stock lengths.
Key Requirements:
- •Profiles run in even stock lengths, commonly 7–16 ft.
- •Baseboard run deducts door and cased openings; crown runs continuous.
- •Order with 10–15% extra for miters, copes, and defect cuts.
IRC R312 — Guards (Railing Length)(IRC R312)
View StandardInternational Residential Code provisions for guards/railing, the linear run of which is taken off in running feet.
Key Requirements:
- •Guards required where a walking surface is more than 30 in above grade.
- •Railing run is the deck/stair perimeter minus the house side and stair openings.
- •Baluster count derives from the linear run and the ≤ 4 in sphere spacing rule.
ASTM D6662 / Decking Coverage(ASTM D6662)
View StandardPerformance standard for polyolefin-based (composite) deck boards, installed with a manufacturer-specified gap that sets board coverage width.
Key Requirements:
- •Boards install with a gap (commonly ⅛–3⁄16 in) for drainage and expansion.
- •Coverage per linear foot = (board face width + gap) ÷ 12 square feet.
- •Square-foot area ÷ that coverage gives the board linear feet to buy.
SMACNA Architectural Sheet Metal (Gutter Runs)(SMACNA)
View StandardSheet Metal and Air Conditioning Contractors’ National Association manual covering gutter and downspout layout, taken off in linear feet of eave.
Key Requirements:
- •Gutter length equals the total eave run the gutter follows.
- •Outlets, end caps, and corners are counted separately from the running feet.
- •Order continuous runs to minimize seams and joints.
Standards Disclaimer: Standards and codes are subject to periodic updates. Always verify current requirements with local building authorities and professional engineers before beginning construction. Links provided are for reference only.
Linear Feet vs. Square Feet
Length-priced vs. coverage-priced material
Material that runs in a line — trim, fencing, gutter, railing, dimensional lumber — is sold by the linear foot. Material that covers a surface — drywall, paint, sheet flooring, sod — is sold by the square foot. Using the wrong unit over- or under-buys badly.
Regional Examples:
Baseboard vs. Crown — Deduct or Not
Openings change the run for some trim, not others
Baseboard stops at every door casing, so you subtract door openings from the perimeter. Crown molding runs continuously around the room over the doors, so you do not deduct — the run is the full perimeter.
Regional Examples:
Stock Lengths Differ by Material
How the running feet are packaged
Trim runs in even lengths up to 16 ft; fence rails and pickets come in 6, 8, and 16 ft; gutters run in 10 ft sections or seamless on-site. The linear feet are the same, but the piece count and offcut waste depend on the stock length.
Regional Examples:
Waste Tracks the Work, Not the Length
Miters and copes drive overage
A miter-heavy trim job around bays and built-ins wastes far more than a long straight fence or gutter. Match the waste factor to the number of cuts, not just the footage.
Regional Examples:
Board Coverage Depends on the Gap
Area-to-linear-feet conversion is gap-sensitive
Converting square feet to board linear feet uses the board face width plus the install gap. A wider gap means more linear feet cover the same area; tongue-and-groove with no gap covers the most per board.
Regional Examples:
Before You Build
- •Contact your local building department for specific requirements
- •Verify frost line depths, wind zones, and seismic requirements for your area
- •Check if permits are required and schedule required inspections
- •Consult with a local contractor familiar with local codes
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Related Calculators
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How to Use This Calculator
- Pick a measure mode: Perimeter (a rectangle), Add up runs (a list of straight segments), or Square feet → linear feet (board coverage).
- Perimeter mode: enter the length and width; the calculator returns 2 × (length + width).
- Runs mode: add a row per straight segment with its feet, extra inches, and how many identical runs.
- Subtract openings where no material runs — doorways for baseboard, gates for fencing. Leave this empty for crown molding, which runs continuously.
- Square-feet mode: enter the area and pick a board (or a custom face width) plus the install gap to convert to board linear feet.
- Optionally pick a stock length (8, 12, 16 ft …) to see how many sticks to buy, and set a waste factor — 10–15% for miter-heavy trim, 5–10% for straight runs.
- Click Calculate to see linear feet to buy, net linear feet, openings subtracted, and pieces, then open the Trim, Fence, Gutters, or Deck calculator.
Linear Feet vs. Square Feet vs. Board Feet
These three units trip people up because they measure different things. Linear feet (running feet) measures LENGTH only — it is what you use for trim, fencing, gutter, railing, and dimensional lumber sold by the running foot, where width does not change the price. Square feet measures AREA (length × width) — drywall, paint, tile, and sheet flooring. Board feet measures VOLUME (thickness × width × length) — the unit hardwood and rough lumber are priced in. A 16-foot board is always 16 linear feet, but its square feet and board feet change with its width and thickness. This calculator stays in the linear lane: it also converts a square-foot area to the linear feet of boards needed to cover it, using the board face width plus the install gap.
Frequently Asked Questions
How do you calculate linear feet?
Linear feet measures length only, so it depends on what you're measuring. For a rectangle (a room or a fenced yard) it's the perimeter: 2 × (length + width) — a 14 × 12 ft room is 2 × (14 + 12) = 52 linear feet. For an irregular layout, add up every straight run: a 40 ft fence side plus two 25 ft sides is 40 + (25 × 2) = 90 linear feet. To convert feet and inches, divide the inches by 12 (12 ft 8 in = 12.67 ft). This calculator does all of that and subtracts openings for you.
What is the difference between linear feet and square feet?
Linear feet measures length only; square feet measures area (length × width). Material that runs in a line — baseboard, crown, fence rail, gutter, deck railing, dimensional lumber — is sold by the linear foot, because a 4-inch board and a 12-inch board of the same length cost the same per running foot. Material that covers a surface — drywall, paint, tile, sheet flooring, sod, roofing — is sold by the square foot. Using the wrong unit over- or under-buys by the width of the material, so match the unit to how the product is sold. The length-only diagram shows length versus area.
How do I convert square feet to linear feet?
You can only convert square feet to linear feet if you know the width of the boards covering the area. The formula is linear feet = area (sq ft) × 12 ÷ (board face width + gap, in inches). For example, 200 sq ft of 5½-inch deck boards installed with a 3⁄16-inch gap is 200 × 12 ÷ 5.6875 = 422 linear feet. Tongue-and-groove flooring with no gap uses just the face width. Set the area, board width, and gap in this calculator's square-feet mode and it does the conversion. The area-to-linear diagram shows LF = area × 12 ÷ board width.
Do I subtract doors and windows from linear feet?
It depends on the trim. For baseboard, yes — subtract every door and cased opening, because the baseboard stops at the casing. For crown molding, no — crown runs continuously around the room over the top of the doors, so you use the full perimeter with no deductions. Windows usually don't affect baseboard (they sit above it) but can interrupt chair rail. Use this calculator's openings section to deduct doorways for baseboard and leave it empty for crown.
How many linear feet of baseboard do I need for a room?
Start with the room perimeter — 2 × (length + width) — then subtract the width of each doorway. A 14 × 12 ft room is 52 linear feet of perimeter; with one 3 ft doorway that's 49 linear feet of baseboard. Add 10–15% waste for miter and cope cuts, so you'd buy about 55 linear feet, or four 14-ft sticks. This calculator's perimeter mode plus the openings deduction gives you the net run and the number of sticks to buy. The perimeter diagram shows perimeter = 2 × (length + width).
Is linear feet the same as lineal feet?
Yes — 'lineal feet' and 'linear feet' mean the same thing: a measurement of length in feet, where 1 linear foot equals 12 inches. 'Linear' is the more common spelling in math and most trades; 'lineal' shows up in the lumber and flooring industries, especially on price lists ('priced per lineal foot'). Both ignore width and thickness and refer only to running length, so you can use the numbers from this calculator interchangeably for either term.
Does this calculator show material prices?
No. Like every calculator on the site, it's pricing-free — it gives you quantities (linear feet, net linear feet, openings subtracted, and pieces to buy), not dollar figures, because prices for trim, fencing, and lumber move constantly by region and grade. Take your linear-foot total to a supplier for a current per-foot or per-stick quote. To finish the take-off with materials and fasteners, hand your number to the Trim, Fence, Gutters, Deck, or Retaining Wall calculator.