Area Calculator
Calculate the area and perimeter of any 2D shape instantly.
Area Calculator
Find the area of any two-dimensional shape. Select your shape, enter the dimensions, and get the area instantly with the formula used — perfect for homework, home improvement projects, or any geometry problem.
How to Use This Calculator
- Select the shape: circle, square, rectangle, triangle, trapezoid, rhombus, ellipse, sector, or parallelogram.
- Enter the required dimensions in consistent units.
- Click Calculate to get the area and perimeter.
Area Formulas
- Square: A = s²
- Rectangle: A = l × w
- Triangle: A = ½ × b × h
- Circle: A = π × r²
- Trapezoid: A = ½ × (b₁ + b₂) × h
- Parallelogram: A = b × h
- Rhombus: A = ½ × d₁ × d₂ (diagonals)
- Ellipse: A = π × a × b (semi-major × semi-minor axes)
- Regular polygon: A = ½ × perimeter × apothem
Example Calculations
- Circle (r=7): A = π × 49 ≈ 153.94 sq units
- Triangle (b=12, h=8): A = ½ × 12 × 8 = 48 sq units
- Trapezoid (b₁=6, b₂=10, h=4): A = ½ × (6+10) × 4 = 32 sq units
- Room 15ft × 12ft: A = 180 sq ft
Common Mistakes to Avoid
- Using diameter instead of radius for circles — Area = πr², not π(d)². If you have the diameter, halve it first.
- Using slant height instead of perpendicular height for triangles — The h in ½bh is the perpendicular height from base to apex, not the slant side length.
- Mixing units — All dimensions must be in the same unit. A room measured in feet gives area in square feet, not square inches.
Frequently Asked Questions
What is the area of an irregular shape?
Break it into regular shapes, calculate each area, then sum them. For truly irregular shapes, use the coordinate/surveyor formula (Shoelace formula) if you have all vertex coordinates.
How do I calculate square footage for flooring?
Measure length and width of each rectangular section in feet, calculate area, sum them. Add 10% for cuts and waste. See our Square Footage Calculator.
What is the difference between area and perimeter?
Area is the space inside a shape (measured in square units). Perimeter is the total length around the outside edge (measured in linear units).
Conclusion
Area calculations are fundamental to real-world geometry — from buying flooring to designing gardens to solving academic problems. This calculator covers every common shape with the correct formula applied automatically.
Related: Surface Area Calculator | Volume Calculator | Circle Calculator | Square Footage Calculator
Geometry Pro-Tip
When working with irregular spaces, try breaking them down into smaller rectangles and triangles. Summing their individual areas will give you the total area of the complex space.
