Quick answer
Square feet = linear feet × width in inches ÷ 12. 100 linear feet of 5.5 inch boards covers 45.833 ft², or 5.093 yd².
Enter the linear feet and the board or material width in inches. The calculator returns area in square feet and yards.
Related tools: Area Converter: Convert square metres, feet, acres, hectares and more. Square Feet to Cubic Yards Calculator: Cubic yards of material covering an area at a depth. Feet and Inches Calculator: Add or subtract two lengths given in feet and inches.
How to use the Linear Feet to Square Feet Calculator
- Enter linear feet (above 0).
- Enter width (in) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Linear feet | A number | > 0 |
| Width | A number, in in | > 0 |
Formula and method
Formula
square feet = linear feet × width (in) ÷ 12
IEEE-754 double precision; shown to the decimals indicated.
Multiply the length by the width in feet.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Linear feet = 100; Width = 5.5.
| Result | Value |
|---|---|
| Area | 45.833 ft² |
| Square yards | 5.093 |
Example 2
Inputs: Linear feet = 250; Width = 12.
| Result | Value |
|---|---|
| Area | 250 ft² |
| Square yards | 27.778 |
Example 3
Inputs: Linear feet = 36; Width = 3.25.
| Result | Value |
|---|---|
| Area | 9.75 ft² |
| Square yards | 1.083 |
The first line is the headline result (area). Below it the linear Feet to Square Feet Calculator lists square yards, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Where it is used
Flooring, decking, siding and trim are often priced by the linear foot, while coverage is stated in square feet. 5.5 ÷ 12 = 0.4583 ft of width, times 100 ft gives 45.83 ft².
Waste
Add 10% for cuts and waste when ordering. If the width is nominal (a 6 inch board is really 5.5), use the actual face width.
How the result changes with linear feet
Holding every other input at the first worked example, this table changes only linear feet. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Linear feet | Area | Square yards |
|---|---|---|
| 50 | 22.917 ft² | 2.546 |
| 100 | 45.833 ft² | 5.093 |
| 200 | 91.667 ft² | 10.185 |
| 400 | 183.333 ft² | 20.37 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Linear feet: entering "0" shows "Linear feet must be greater than 0." beside that field and no result.
- Width: entering "0" shows "Width must be greater than 0." beside that field and no result.
Choosing between the Linear Feet to Square Feet Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Area Converter](/converters/area-converter/) | value, from and to | Cent (1/100 acre) → Square metre (m²) |
| [Square Feet to Cubic Yards Calculator](/converters/ft2-yd3/) | area and depth | Volume |
| [Feet and Inches Calculator](/converters/feet-inches-calculator/) | first length: feet, first length: inches and second length: feet | Result |
| [Square Footage Calculator](/construction/square-footage-calculator/) | length, width and unit | Area |
| [Linear Interpolation Calculator](/math/linear-interpolation/) | x₁, y₁ and x₂ | Interpolated y |
Background: unit conversion
Many customary units are defined exactly in terms of metric ones: since the 1959 International Yard and Pound Agreement an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg (NIST SP 811 lists these). So most length and mass conversions are exact apart from the rounding of the displayed result.
To convert, multiply the value by the source unit's factor to reach the base unit, then divide by the target unit's factor; the unit table on this page lists every factor used. Temperature and fuel economy are the exceptions, because they are not simple multiples.
Assumptions and limitations
- Width is in inches
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for linear feet and width to confirm this.
Frequently asked questions
How many linear feet make a square foot?
For a 6 inch wide board, 2 linear feet make one.
Does it work for lumber?
Yes, use the actual face width.
Why width in inches?
Board widths are usually quoted in inches.
What does the Linear Feet to Square Feet Calculator calculate?
Square feet covered by a length of material of a given width. It returns Area and Square yards.
What formula does the Linear Feet to Square Feet Calculator use?
square feet = linear feet × width (in) ÷ 12. Multiply the length by the width in feet.
What do I need to enter in the linear Feet to Square Feet Calculator?
You enter Linear feet and Width (in).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Width is in inches.
What is an example of a linear Feet to Square Feet result?
With linear feet 100 and width 5.5, the area is 45.833 ft².
Related calculators
- Area Converter — Convert square metres, feet, acres, hectares and more.
- Square Feet to Cubic Yards Calculator — Cubic yards of material covering an area at a depth.
- Feet and Inches Calculator — Add or subtract two lengths given in feet and inches.
- Linear Interpolation Calculator — Interpolate a value between two known points.
- Square Diagonal Calculator — Diagonal of a square.
Sources
- OpenStax, Prealgebra 2e (Rice University): fractions, decimals, percents, ratios and rounding
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.