Калкулатор за квадратни футове
Изчислете площта на всяко пространство за секунди. Въведете размерите по-долу за мигновен и точен резултат в квадратни футове.
Изчислете площ в квадратни футове
All Square Foot Calculators
Choose a specialized calculator for your specific project type.
Square Foot Calculator Formula
A square foot calculator uses the fundamental surface area formula to compute total space in square feet (ft²):
This formula applies to rectangular and square shapes measured in feet (ft). The result represents the total area of a flat, two-dimensional surface.
Each formula converts measured dimensions into square feet (sq ft), square meters (m²), square yards (yd²), square inches (in²), and acres.
How to Calculate Square Foot
To calculate square foot, measure the length and width of the space in feet and multiply the two values together.
Basic Formula for Area: Area is the amount of space occupied by a two-dimensional surface (floor, wall, playground, or field).
An L-shaped or irregular floor plan requires splitting the space into 2 or more rectangles. Calculate each rectangle area separately, then add the results together for the total square footage.
Area Conversion
Measure your space in any unit, calculate the area, then convert the result to the unit you need. Measure in inches or centimeters, calculate area in square inches or square centimeters, then convert the final answer to square feet or square meters.
| Unit | Equals |
|---|---|
| 1 acre | 43,560 square foot |
| 1 square yard | 9 square foot |
| 1 square meter | 10.76 square foot |
| 1 square inch | 0.00064516 square foot |
| 1 square foot | 0.0929 square meter |
| 1 square foot | 144 square inch |
Area Formulas for Different Shapes
Drag the sliders in each diagram to see how area changes in real time.
Square Shape
The formula to calculate the area of a square is side length × side length. A square with 8-foot (2.44 m) sides has an area of 64 square feet (5.95 square meters).
Rectangle Shape
A rectangle measuring 15 feet long and 10 feet wide has an area of 150 square feet (13.94 sq m). The rectangle area formula is the most common square footage calculation for rooms, lots, and construction projects.
Rectangle Border Shape
Total Area = (L + 2×Border) × (W + 2×Border)
Area = Total − Inner
Use the rectangle border formula for bordered surfaces, including picture frames, garden borders, and walkway edges. A 10 × 6 ft garden bed with a 2-ft wide border has a border area of (14 × 10) − (10 × 6) = 80 sq ft.
Circle Shape
This formula uses diameter — the full width across the circle. A circular patio with a 10-foot diameter has an area of 3.14159 × 5² = 78.54 square feet (7.30 sq m).
Divide the diameter by 2 to get the radius. For hand calculations, use π = 3.14159265359 for higher accuracy on larger areas.
Circle Border Shape (Ring)
Outer Area = π × (Outer ÷ 2)²
Inner Area = π × (Inner ÷ 2)²
Area = Outer Area − Inner Area
Use the circle border formula for ring-shaped surfaces, including circular walkways and decorative borders around round patios.
Annulus Shape
Inner Area = π × (Inner ÷ 2)²
Area = Outer Area − Inner Area
The Circle Border and Annulus are the same shape. Circle border area is calculated using border width; annulus area is calculated using the outer diameter directly.
Triangle Shape
Triangles can be calculated two ways — by edge lengths (Heron's formula) or by base and height.
Triangle with Edge Lengths
Area = √{ s × (s−a) × (s−b) × (s−c) }
This is Heron's formula. The sides of the triangle do not need to be equal. This formula works for any triangle — equilateral, isosceles, and scalene.
Triangle with Base & Height
A triangular area with a base of 8 ft (2.44 m) and a height of 6 ft (1.83 m) has an area of ½ × 8 × 6 = 24 square feet (2.23 sq m).
Trapezoid Shape
The values a and b are the two parallel sides; h is the perpendicular height between them. A trapezoid with parallel sides of 12 ft and 8 ft and a height of 5 ft has an area of [(12+8) ÷ 2] × 5 = 50 sq ft.
Sector Shape
A sector is a "pie slice" portion of a circle defined by two radii and an arc. A sector with a 6-ft radius and 90° central angle has an area of (90÷360) × π × 36 = 28.27 sq ft.
Parallelogram Shape
A parallelogram with a base of 10 ft and a height of 7 ft has an area of 70 square feet. The height is the perpendicular distance between the two parallel sides — not the slanted side length.
Wall and Window Shape
Window Area = Window Height × Width
Net Area = Wall Area − Window Area
Use this formula when painting a house or installing siding. Subtract the area of windows and doors from the total wall area to get the paintable surface.
This also works for walls with doors — enter door dimensions in the Window Width and Window Height fields.
Cathedral Wall (Right Trapezoid)
This calculation covers a wall with a sloped top edge, typical of rooms with cathedral ceilings. The geometric shape is a right trapezoid. Alternatively, break the cathedral wall into a rectangle and a triangle, then add both areas together.
Calculating Cost Per Square Foot
Painting a house, installing flooring, and building a home all use the square footage of the property to determine cost, material quantities, and labor requirements.
Painting a House
Professional house painters base price quotations on the square footage of a property. Measuring square footage yields accurate estimates of the amount of paint required, even for homeowners painting the house themselves.
Total cost encompasses more factors than the amount of paint required, including the cost of materials such as brushes, turpentine, and any materials necessary for preparing, mixing, applying, and cleaning up paint. These considerations are included in a quote from a professional painter, in addition to labor costs. The larger the square footage of a property or area, the higher the cost required to paint the property.
Primer Coverage: Paint primer helps paint adhere more effectively to surfaces including wood, metal, and drywall. Primer generally covers less area than topcoat paint. Estimated coverage amounts range from 200 to 400 square feet (18.58 to 37.16 m²) per gallon, depending on application method and surface porosity.
Flooring Installation & Material Guide
There are 3 main categories of flooring materials commonly used for installation: wood, laminate, and tile. Flooring costs vary depending on material quality, durability, and installation complexity.
Building a Home
Building plans and visiting model homes help you gain a better understanding of what square footage works best for your family's preferences during renovation or new construction.
The cost of building a home varies based on materials, foundation design, roof pitch, and regional labor rates. Cost per square foot is calculated by dividing total builder quotes by total indoor square footage. Outside costs include municipal permits, site preparation, utility hookups, and insurance.
Frequently Asked Questions
A square foot calculator is an online tool that computes the area of a space in square feet (ft²). Enter length and width measurements, and the calculator multiplies the values to return the total square footage. This calculator supports rectangles, circles, and triangles, and converts results to square meters, square yards, square inches, and acres.
Multiply the length by the width of the space, with both measurements in feet. A room 12 feet long and 10 feet wide has an area of 120 square feet (12 × 10 = 120 sq ft). For circles, use π × radius². For triangles, use ½ × base × height.
Convert inches to feet by dividing by 12, then multiply length by width. A room 10 feet 6 inches long is 10.5 feet (6 ÷ 12 = 0.5). Multiply 10.5 × 8 = 84 square feet. Use the Feet & Inches calculator for separate feet and inches input fields.
The formula is area = length × width. Measure the length and width of the space in feet, then multiply the two numbers. A space 15 feet long and 10 feet wide equals 150 square feet (15 × 10 = 150 sq ft).
Yes, split the irregular shape into simple shapes such as rectangles, triangles, and circles. Calculate the area of each shape separately, then add all the areas together for the total square footage. The Odd Shapes calculator automates this process.
Measure the length and width of each room in feet and multiply to get the area. Add 10% to 15% extra for waste from cuts, mistakes, and future repairs. The Flooring calculator includes a built-in waste factor for hardwood, laminate, vinyl, and carpet.
Measure wall width and height in feet, then multiply. For room walls, multiply total perimeter by ceiling height, then subtract door and window areas. The Wall calculator automatically deducts openings and estimates paint gallons.