1. Select your shape
Choose from rectangle, circle, triangle, trapezoid, L-shape, annulus, or wall-and-window layouts to match your project.
Getting started
How to Calculate Square Footage
Square footage is a measurement of area where the dimensions, like length and width, are in feet. The Square Foot Calculator finds the area of a building, home, garden, or construction project by applying the correct formula for each shape. Enter your measurements, select a shape, and the calculator returns results in square feet (sq ft), square inches (sq in), square yards (sq yd), square meters (sq m), and acres.
To calculate square footage for a rectangular room, measure the length and width in feet, then multiply: length × width = area in square feet. A room that measures 15 feet (4.57 meters) by 20 feet (6.10 meters) has an area of 300 square feet (27.87 square meters).
Irregular spaces like an L-shape require splitting the floor into 2 or more rectangular sections. Calculate the area of each section separately, then add the results together for total square footage.
2. Enter your measurements
Input dimensions in feet, inches, yards, meters, or centimeters. The Square Footage Calculator converts units automatically.
3. Get area and cost
View results in square feet, square yards, square meters, and acres. Add a material price per unit to estimate total project cost.
Quick reference
Reference
1 acre = 43,560 square feet
1 square yard = 9 square feet
1 square meter = 10.764 square feet
1 square inch = 0.00064516 square feet
Material pricing
Calculate Cost of Materials
Enter the price per square foot of material to estimate total cost. The calculator accepts pricing in square feet, square inches, square yards, or square meters and converts to the correct total based on your area.
There are 2 steps to calculate material cost:
- Enter the price per unit area. For tiling projects, enter the price per box and the number of square feet each box covers. For carpet, enter the cost per square yard. For flooring installation with hardwood or laminate, enter the cost per square foot.
- Select the unit of area that matches your pricing. The Square Foot Calculator multiplies your total area by the unit price to produce an estimated material cost, including labor costs when added to the per-unit price.
To calculate the volume of bulk materials like mulch or gravel for landscaping, convert area to cubic yards or cubic meters by multiplying the area by the depth of material.
Core formula
Basic Formula for Area
Area is the amount of space occupied by a 2-dimensional shape. The shape could be a floor, a wall, a playground, or a field. The simplest formula for area applies to any rectangular shape:
Area = Length × Width
Measure the length and width of the space in feet. Multiply the two values to get the area in square feet. A rectangular room that is 12 feet (3.66 meters) long and 10 feet (3.05 meters) wide has an area of 120 sq ft (11.15 sq m).
Square yardage is area measured in yards, and square meters is area measured in meters. Measure in feet, find the area in square feet, then convert to the unit you need.
For an L-shape room, split the floor into 2 rectangular sections, calculate each area, and add the results. Convert all measurements to the same unit before multiplying, if your dimensions are in different units like inches and feet.
Basic Length Conversion
Convert other units of measure to feet with these 4 formulas:
| From | To Feet | Formula |
|---|---|---|
| Inches | Feet | Divide by 12 |
| Yards | Feet | Multiply by 3 |
| Meters | Feet | Multiply by 3.28084 |
| Centimeters | Feet | Divide by 30.48 |
For example, 48 inches ÷ 12 = 4 feet. A measurement of 5 meters × 3.28084 = 16.40 feet. The Square Foot Calculator handles these conversions automatically when you select the input unit.
Unit conversion
Area Conversion
Measure your space in inches or centimeters, calculate area in square inches or square centimeters, then convert to any unit you need, including square feet, square yards, square meters, or acres.
| Unit | Square Feet Equivalent |
|---|---|
| 1 sq ft | 144 sq in |
| 1 sq yd | 9 sq ft |
| 1 sq m | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
A 300 sq ft room equals 33.33 sq yd, 27.87 sq m, or 43,200 sq in. The Square Footage Calculator displays all conversions at once so you can compare units for flooring, carpet, or tiling projects without manual math.
Shape formulas
Area Formulas for Different Shapes
The Square Foot Calculator supports 11 shape formulas for construction, interior design, landscaping, and flooring projects. Each formula below includes a diagram with labeled dimensions.
Square Shape
Calculate square foot of a square
Using measurements in feet: Area (ft²) = Side Length². The formula to calculate area of any box shape is length × width. Since length equals width for a square, area is the side length squared. A square with 8-foot (2.44-meter) sides has an area of 64 sq ft.
Rectangle Shape
Calculate square foot of a rectangle
Using measurements in feet: Area (ft²) = Length × Width. This is the most common formula for calculating square footage of a rectangular room, floor, wall, or field. A room 15 feet (4.57 meters) long and 12 feet (3.66 meters) wide has a Rectangle Area of 180 sq ft (16.72 sq m).
Rectangle Border Shape
Calculate square foot of a rectangle border
Using measurements in feet:
- Inner Area (ft²) = Length × Width
- Total Area (ft²) = (Length + 2 × Border Width) × (Width + 2 × Border Width)
- Border Area (ft²) = Total Area − Inner Area
Use this formula for painting a border, installing trim, or measuring a walkway around a rectangular garden. A 10 ft × 8 ft (3.05 m × 2.44 m) area with a 1-foot border has a border area of 40 sq ft.
Wall and Window Shape
Calculate square foot of a wall minus window
Using measurements in feet:
- Wall Area (ft²) = Wall Height × Wall Width
- Window Area (ft²) = Window Height × Window Width
- Area (ft²) = Wall Area − Window Area
To subtract multiple windows of the same size from one wall, multiply window width by the number of windows and enter the total as window width. A wall 12 ft × 8 ft (3.66 m × 2.44 m) with a 3 ft × 4 ft window has a paintable area of 84 sq ft. Use this shape for walls with doors or other openings during painting or flooring installation projects.
Cathedral Wall
Calculate square foot of a cathedral wall (right trapezoid)
Using measurements in feet: Area (ft²) = ½ × Width × (Height 1 + Height 2). This formula applies to a wall with a sloped top edge, typical of rooms with a cathedral ceiling. The geometric shape is a right trapezoid. A cathedral wall 14 feet (4.27 meters) wide with heights of 8 feet (2.44 meters) and 12 feet (3.66 meters) has an area of 140 sq ft.
Circle Shape
Calculate square foot of a circle
Using measurements in feet: Area (ft²) = π × (Diameter ÷ 2)², where π = 3.14159. This formula uses the diameter (the full width of the circle). Divide the diameter by 2 to get the radius: diameter = 2 × radius. A circular patio with a 10-foot (3.05-meter) diameter has an area of 78.54 sq ft. The Square Foot Calculator uses a high-precision π constant for accurate results on larger landscaping and construction projects.
Circle Border Shape
Calculate square foot of a circle border
Using measurements in feet:
- Outer Diameter = Inner Diameter + (2 × Border Width)
- Outer Area (ft²) = π × (Outer Diameter ÷ 2)²
- Inner Area (ft²) = π × (Inner Diameter ÷ 2)²
- Border Area (ft²) = Outer Area − Inner Area
Use this formula for circular walkways, garden borders, and ring-shaped landscaping features around a home.
Annulus Shape
Calculate square foot of an annulus
Using measurements in feet:
- Outer Area (ft²) = π × (Outer Diameter ÷ 2)²
- Inner Area (ft²) = π × (Inner Diameter ÷ 2)²
- Annulus Area (ft²) = Outer Area − Inner Area
The circle border and annulus are the same shape. Circle border area uses border width as input, while annulus area uses the outer diameter. An annulus with a 20-foot (6.10-meter) outer diameter and 12-foot (3.66-meter) inner diameter has an area of 201.06 sq ft.
Triangle Shape
Calculate square foot of a triangle
Using measurements in feet: Area = √[s(s − a)(s − b)(s − c)], where s = (a + b + c) ÷ 2. This is Heron's formula. The 3 sides of the triangle do not need to be the same length. Enter the length of each side in feet and the Square Foot Calculator returns the area in square feet, square yards, and square meters. Use this for corner plots, angled architectural sections, and triangular installation zones.
Triangle Shape
Calculate square foot of a triangle using base and height
Using measurements in feet: Area (ft²) = ½ × Base × Height. This formula is simpler than Heron's formula and works when you know the base and the perpendicular height of the triangle. A triangle with a 10-foot (3.05-meter) base and 6-foot (1.83-meter) height has an area of 30 sq ft (2.79 sq m).
Trapezoid Shape
Calculate square foot of a trapezoid
Using measurements in feet: Area (ft²) = [(a + b) ÷ 2] × h. The variables a and b are the 2 parallel sides, and h is the perpendicular height between the parallel sides. A trapezoid with parallel sides of 8 feet (2.44 meters) and 14 feet (4.27 meters), with a height of 6 feet (1.83 meters), has an area of 66 sq ft (6.13 sq m).
Room Shape
Calculate square foot of a room
Using measurements in feet: Area (ft²) = Room Length × Room Width. Measure the longest wall for length and the perpendicular wall for width. A standard rectangular room that is 12 feet (3.66 meters) long and 10 feet (3.05 meters) wide has an area of 120 sq ft (11.15 sq m). Door and window openings do not reduce floor area because the floor extends under the opening. For rooms with closets or alcoves, measure each rectangular section separately and add the areas together.
Waste factor
Adding 10% Surplus for Materials
Add a 10% surplus to your calculated area to account for material waste during cutting, breakage, and pattern matching. This waste factor applies to flooring, carpet, tiling projects, and landscaping materials.
Original Area
100 sq ft
+10%
Order Amount
110 sq ft
Total Material = Area × 1.10
A room with 200 sq ft of floor area needs 220 sq ft of material: 200 × 1.10 = 220 sq ft. Increase the surplus to 15% (multiply by 1.15) for diagonal flooring installation patterns or complex tiling projects with many cuts. The Square Foot Calculator includes a waste factor field for this calculation.
Quick reference
Summary of Calculations
This table summarizes all 11 area formulas supported by the Square Footage Calculator. Each formula uses measurements in feet to produce results in square feet.
| Shape | Formula | Example (ft) | Area (sq ft) |
|---|---|---|---|
| Square | Side² | 10 × 10 | 100 |
| Rectangle | Length × Width | 15 × 12 | 180 |
| Rectangle Border | Total − Inner | 12×10 outer, 10×8 inner | 40 |
| Wall − Window | Wall − Window | 12×8 wall, 3×4 window | 84 |
| Cathedral Wall | ½ × w × (h1 + h2) | 14 wide, h1=8, h2=12 | 140 |
| Circle | π × (d ÷ 2)² | d = 10 | 78.54 |
| Circle Border | Outer − Inner circle | d=10, border=1 | 34.56 |
| Annulus | π(R² − r²) | D=20, d=12 | 201.06 |
| Triangle (3 sides) | Heron's formula | a=10, b=10, c=10 | 43.30 |
| Triangle (b × h) | ½ × Base × Height | b=10, h=6 | 30 |
| Trapezoid | [(a+b) ÷ 2] × h | a=8, b=14, h=6 | 66 |
FAQ
Frequently Asked Questions
How do I calculate square footage for different shapes?
Multiply length × width for rectangles and squares, use π × (diameter ÷ 2)² for circles, ½ × base × height for triangles, and [(a + b) ÷ 2] × h for trapezoids. The Square Foot Calculator applies these formulas automatically when you select a shape and enter your measurements. For irregular spaces, split the area into 2 or more standard shapes, calculate each section, and add the results.
Can I convert between square feet and other units using this calculator?
Yes, the Square Footage Calculator converts square feet to square yards, square inches, square meters, and acres automatically. Enter your dimensions in any supported unit, including feet, inches, yards, meters, or centimeters, and the calculator displays all conversions at once. 1 square yard = 9 sq ft. 1 square meter = 10.764 sq ft. 1 acre = 43,560 sq ft.
How do I measure for a construction project?
Measure the length and width of each surface in feet, enter the dimensions into the Square Foot Calculator, and the calculator returns the area in square feet along with estimated material quantity and cost. For construction projects with irregular floor plans, measure each rectangular section separately. Add a 10% waste factor for materials like flooring, tiling, and carpet to cover cutting and breakage.
Can this calculator help with landscaping projects?
Yes, the Square Foot Calculator estimates area and material needs for gardens, walkways, patios, and other landscaping features. Select the shape that matches your project, whether rectangular for a garden bed, circular for a patio, or annulus for a ring-shaped pathway. Enter the price per square foot of sod, mulch, or pavers to get an estimated total cost.
How many feet in a square foot calculator?
1 square foot equals an area of 1 foot × 1 foot, which is 144 square inches or 0.0929 square meters. A square foot is a unit of area, not length. The term "square" means the measurement covers a flat 2-dimensional space. The Square Foot Calculator takes length and width measurements in feet and returns the total area in square feet.
How is running square feet calculator?
Running feet (also called linear feet) measure length in a straight line, while square feet measure area (length × width). A running foot is 1-dimensional. A square foot is 2-dimensional. To convert running feet to square feet, multiply the running length by the width of the material. For example, 20 running feet of 2-foot-wide carpet = 40 square feet.
What is square foot calculator?
A square foot calculator is an online tool that calculates the area of a space in square feet based on the dimensions you enter. The Square Foot Calculator supports 11 shapes, including rectangle, circle, triangle, trapezoid, L-shape, annulus, and wall-minus-window layouts. Enter measurements in feet, inches, yards, meters, or centimeters. The calculator returns area in square feet, square yards, square meters, and acres, and estimates material cost when a price per unit is provided.
How many square feet are in a 12×12 room?
A 12 × 12 room is 144 square feet because 12 feet × 12 feet = 144 sq ft. That equals 16 square yards, 13.38 square meters, or 20,736 square inches. A 12 × 12 foot room is a common bedroom or home office size used in building and interior design projects.
Can I use this square foot calculator for flooring?
Yes, the Square Foot Calculator works for all flooring types, including hardwood, laminate, tile, vinyl plank, and carpet. Measure the floor length and width, enter the dimensions, and the calculator returns the area in square feet. Add a material price per square foot or per square yard to estimate total flooring installation cost. Include a 10% waste factor for cuts and breakage.
Does the calculator estimate material cost?
Yes, enter a price per square foot, square yard, or square meter and the Square Foot Calculator multiplies the total area by the unit price to produce an estimated material cost. This works for flooring, carpet, tiling projects, painting, landscaping materials, and any surface-based building project. Add labor costs to the per-unit price for a more complete estimate.