🪵 Flooring & Carpet
Measure every room, subtract permanent exclusions when appropriate, then add 5–15% for cuts, matching patterns, and future repairs.
Square Footage Calculator
Calculate square footage for rooms, walls, lots, gardens, flooring, and construction projects. Choose a shape, mix measurement units, add quantity and waste, then estimate material cost.
11 Area Shapes
5 Area Units
Waste & Cost
Area Measurements
Rectangle Measurements
Formula
Area = Length × Width
Project Adjustments
%
Optional Material Cost
$
Live Results
Total square footage
120
ft²
Rectangle · quantity 1 · 0% waste
Square Yards
13.333
yd²
Square Meters
11.148
m²
Square Inches
17,280
in²
Acres
0.002755
ac
One shape120 ft²
After quantity120 ft²
Extra for waste0 ft²
Tip:For irregular spaces, split the project into simple shapes, calculate each section, and add the totals.
📐 How to Calculate Square Footage
Square footage measures two-dimensional area in square feet. For a rectangle, convert the length and width to feet and multiply them. If a room or lot is irregular, divide it into rectangles, triangles, circles, or other simple sections, calculate each area, and add the results.
The calculator converts each measurement independently, so a length entered in feet can be paired with a width entered in inches, yards, meters, or centimeters. Quantity multiplies the selected shape, while the waste factor adds material allowance for cuts, breakage, seams, and installation errors.
1Measure
Measure the dimensions at their widest relevant points and record each unit accurately.
2Calculate
Apply the matching area formula, then multiply by the number of identical areas.
3Plan Materials
Add a practical waste percentage and multiply by the material price per square unit.
▦ Square Footage Formulas for Common Shapes
| Shape | Area Formula | Typical Use |
|---|---|---|
| Rectangle / Square | L × W | Rooms, floors, lots |
| Rectangle Border | (L + 2b)(W + 2b) − LW | Borders, frames, paths |
| Circle | πr² | Round patios, tables |
| Ring / Annulus | π(R² − r²) | Circular borders, tracks |
| Triangle (3 sides) | √[s(s−a)(s−b)(s−c)] | Irregular triangular sections |
| Triangle (base/height) | ½bh | Gables, simple triangles |
| Trapezoid | ½(a + b)h | Sloped lots, wall sections |
| Sector | (θ/360)πr² | Curved beds, fan shapes |
| Parallelogram | bh | Slanted panels, lots |
| Wall minus opening | Wall − Opening | Paint, siding, wallpaper |
| Cathedral wall | ½w(h₁ + h₂) | Sloped ceiling walls |
Area Conversion Reference
43,560 ft²
1 acre
9 ft²
1 square yard
10.7639 ft²
1 square meter
144 in²
1 square foot
🏠 Using Square Footage in Real Projects
🎨 Paint & Wall Coverings
Calculate wall area, subtract doors and windows, and divide by the product coverage rate. Primer often has a different coverage rate than paint.
🧱 Tile & Panels
Use total adjusted square footage to estimate tile, backer board, wall panels, ceiling panels, or sheet materials.
🌿 Landscaping
Measure lawns, gardens, patios, paths, and circular beds before ordering sod, seed, pavers, or landscape fabric.
🏗️ Building Estimates
Square footage supports early comparisons for construction, roofing, siding, and finish materials, though labor and design can change final cost.
💰 Cost per Square Foot
Multiply the adjusted area by a quoted price per square foot, yard, meter, inch, or acre to compare material options consistently.
Choosing a Waste Factor
5%
Simple rectangular layouts with repeatable cuts and reliable measurements.
10%
A common allowance for flooring, tile, carpet, and wall covering projects.
15%+
Diagonal patterns, irregular rooms, natural materials, or projects with many corners.
❓ Square Footage Calculator FAQ
How do I calculate square footage?
For a rectangle, measure length and width in feet and multiply them: square feet = length × width. For other shapes, choose the matching formula in the calculator. Convert mixed units before multiplying, or let this tool convert each measurement automatically.
How do I calculate square footage for an irregular room?
Split the room into simple rectangles, triangles, circles, or trapezoids. Calculate each section separately, then add the areas. For an L-shaped room, two rectangles are usually enough.
How many square feet are in an acre?
One acre equals 43,560 square feet. It also equals 4,840 square yards or approximately 4,046.856 square meters.
How do I convert square meters to square feet?
Multiply square meters by 10.7639. To convert square feet to square meters, multiply by 0.09290304.
How much extra flooring or tile should I buy?
A 10% waste factor is common for straightforward flooring and tile installations. Use 5% for very simple layouts and 15% or more for diagonal patterns, irregular spaces, fragile material, or complex cuts.
Do I include closets in a room’s square footage?
Include closets when the project material continues through them, such as carpet or flooring. Exclude areas that will not receive the material, such as fixed cabinets or open stair voids, according to your project plan.
How do I estimate cost per square foot?
Multiply the total adjusted square footage by the material price per square foot. If the supplier quotes another area unit, select that unit beside the price and the calculator will convert the total before estimating cost.
Can I subtract doors and windows from wall area?
Yes. Choose Wall Minus Opening, enter the full wall dimensions, then enter the combined opening dimensions. For several different openings, calculate their areas separately and subtract the combined total.
What is the difference between square feet and linear feet?
Square feet measure two-dimensional area, while linear feet measure one-dimensional length. A 10 ft by 8 ft wall is 80 square feet but has a 36-linear-foot perimeter.
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