How to Calculate Linear Feet
A linear foot is simply 12 inches of length measured in a straight line. Learning how to calculate linear feet is essential for home improvement, construction estimating, freight shipping, and buying materials like lumber, fencing, pipe, and trim. This guide covers every common scenario with formulas, worked examples, and common mistakes to avoid.
Industry data: According to RSMeans construction cost data, contractors waste an average of 12% of purchased linear-foot materials due to measurement errors, improper waste factors, and on-site cutting mistakes. For a $5,000 fencing project, that's $600 in preventable waste. Accurate linear foot measurement — the focus of this guide — is the single most effective way to control material costs. The National Lumber and Building Material Dealers Association (NLBMDA) reports that linear foot miscalculation is the #1 cause of material shortages on residential job sites, accounting for 34% of emergency supplier runs.
What Is a Linear Foot?
A linear foot (abbreviated LF or ln ft) is a measurement of 12 inches of length. Unlike square feet, which measures area (length × width), linear feet only measures distance in one dimension. Think of running a tape measure in a straight line — whatever it reads in feet is your linear feet.
A 10-foot-long board is 10 linear feet regardless of how wide it is. The board could be 4 inches wide or 12 inches wide — it's still 10 linear feet. This is the fundamental concept: linear feet ignores width entirely.
12 inches
= 1 linear foot
3 feet
= 1 linear yard
0.3048 meters
= 1 linear foot
Basic Formula: How to Calculate Linear Feet from Inches
If you measure something in inches and need linear feet, divide by 12. This is the most fundamental linear foot calculation.
Worked Examples
| Measurement (inches) | Calculation | Linear Feet |
|---|---|---|
| 24 in | 24 ÷ 12 | 2 LF |
| 36 in | 36 ÷ 12 | 3 LF |
| 48 in | 48 ÷ 12 | 4 LF |
| 96 in | 96 ÷ 12 | 8 LF |
| 120 in | 120 ÷ 12 | 10 LF |
| 144 in | 144 ÷ 12 | 12 LF |
How to Calculate Linear Feet from Square Feet
When you know the area (square feet) and the material width, you can calculate linear feet:
The width MUST be in feet. If you know the width in inches, divide inches by 12 first.
Example: Flooring
A 200 sq ft room needs hardwood planks that are 5 inches wide. First convert width: 5 inches ÷ 12 = 0.417 feet. Then: 200 ÷ 0.417 = 480 linear feet of flooring. Add 10% for waste: order roughly 530 linear feet.
Example: Decking
A 300 sq ft deck using 5.5-inch-wide deck boards (actual width of a 5/4×6 board). Width in feet = 5.5 ÷ 12 = 0.458 ft. Linear feet needed = 300 ÷ 0.458 = 655 LF. Add 15% for gaps and waste: order approximately 753 LF.
How to Calculate Linear Feet for Fencing
Fencing is the most straightforward linear foot calculation — it's simply the length of your fence line.
- Measure the perimeter: Use a measuring wheel (most accurate for long distances), a 100-foot tape measure, or measure from a property survey. Walk the exact fence line, not the property line — they may differ by setback distances.
- Account for terrain: On flat ground, measured distance = linear feet. On sloped terrain, add 5-15% extra because fence panels must step down or be racked to follow grade. A 200-foot fence line on a moderate hill typically needs 215-230 LF of material.
- Subtract gates: A 4-foot walk gate replaces 4 linear feet of fence. A 12-foot double drive gate replaces 12 linear feet. But each gate requires its own posts — gates don't reduce post count.
- Add for corners and ends: Each corner and end post requires extra hardware and sometimes a brace panel. Posts are spaced every 6-8 feet for wood, 10 feet for chain link.
How to Calculate Linear Feet for Freight Shipping
LTL (Less-Than-Truckload) carriers charge by the linear foot of trailer space your shipment occupies. This is different from weight-based pricing and is used when freight is light but bulky.
- Measure each pallet: Standard GMA pallet is 48 inches long. When loaded lengthwise in a trailer, it occupies 4 linear feet of trailer space.
- Calculate total trailer feet: Total LF = (Pallet length in inches ÷ 12) × Number of pallets. Four standard 48-inch pallets = (48/12) × 4 = 16 linear feet of trailer space.
- Know the linear foot rule: If freight weighs less than 6-8 pounds per cubic foot, carriers apply the linear foot rule instead of weight. They charge a minimum rate per linear foot regardless of actual weight.
- Standard trailer capacity: A 53-foot dry van holds 48-50 linear feet of palletized freight (allow room for loading). A 28-foot pup trailer holds 24-26 LF.
How to Calculate Linear Feet for Countertops
Kitchen countertops are priced by the linear foot because the depth is standardized at 25.5 inches.
- Measure each section along the back wall: Start at one end of a countertop run and measure to the other end in feet. This is your linear feet for that section. Do NOT measure the front edge — always the back wall.
- Count every section separately: Main runs, islands, peninsulas, and bar tops are each a separate section. Sum all sections for total LF.
- Include appliance gaps: The space over a dishwasher or trash compactor counts as countertop linear feet — the stone spans across it.
- Standard overhang is included: The 1.5-inch front overhang is built into the 25.5-inch standard depth. Bar overhangs (12-18 inches) are an upgrade and may be priced differently.
Tools for Measuring Linear Feet
| Tool | Best For | Accuracy |
|---|---|---|
| Measuring Wheel | Fencing, long property lines | ±1 ft per 100 ft |
| 100-ft Tape Measure | Room perimeters, decking | ±¼ inch |
| Laser Distance Measurer | Interior walls, high ceilings | ±1/8 inch |
| GPS App / Aerial Photo | Rough estimates, large properties | ±10-20 ft |
| Property Survey / Plat Map | Legal boundaries | Survey-grade |
Common Mistakes When Calculating Linear Feet
Mistake 1: Confusing Linear Feet with Square Feet
Linear feet measures length only. Square feet measures area (length × width). A 10-foot board is always 10 LF — regardless of its width. But its square footage changes with width. Ordering 10 "feet" of flooring when you actually need 10 square feet of flooring will leave you short by a factor of the plank width.
Mistake 2: Measuring in a Straight Line Over Terrain
A fence that goes up and down a hill is longer than the straight-line distance on a map. A 100-foot straight-line property boundary that traverses a 20-foot rise might need 103-105 linear feet of fence. Always measure along the ground, not the map.
Mistake 3: Forgetting Waste Factor
Almost every material needs extra for cuts, mistakes, and pattern matching. Baseboard: 5-7% for miter cuts. Flooring: 10-20% depending on layout. Siding: 10-12% for windows and door cuts. Fencing: 5-10% for gates and corners. Not adding waste means you will run short — and a second trip to the lumberyard costs time and delivery fees.
Mistake 4: Not Converting Inches to Feet
All linear foot formulas require widths in feet. A 6-inch-wide board is 0.5 feet, not 6 feet. If you plug in "6" as the width instead of 0.5, you'll order 12× too little material. Before doing any LF calculation, convert all inch measurements to feet (inches ÷ 12).
Try Our Free Linear Feet Calculator
Calculate linear feet for your specific project with our easy-to-use online tools. Each calculator includes the correct waste factor for your material.