Area Calculator
Calculate the area and perimeter of common 2D geometric shapes: rectangles, triangles, circles, sectors, trapezoids, ellipses, and regular polygons.
Rectangle & Square Area
Enter length and width to calculate total area, perimeter, and diagonal distance.
Triangle Area Calculator
Choose a calculation method based on your available triangle measurements.
Circle, Sector & Annulus Area
Calculate full circle area, circular sector area, arc length, or annulus area.
Trapezoid & Parallelogram Area
Compute areas for four-sided quadrilaterals with parallel sides.
Ellipse & Regular Polygon Area
Determine area and perimeter for elliptical curves or multi-sided regular polygons.
How to Use the Area Calculator
Select the tab corresponding to your geometric shape. Input the requested side lengths, radii, or angles, and click Calculate Area to receive full step-by-step mathematical computations.
- Rectangle Area: A = w × l
- Triangle Area: A = ½ × b × h or Heron's Formula A = √(s(s-a)(s-b)(s-c))
- Circle Area: A = πr²
- Trapezoid Area: A = ½ × (a + b) × h
- Ellipse Area: A = π × a × b
Frequently Asked Questions (FAQ)
Area measures the total two-dimensional space bounded within a closed geometric shape. It is measured in square units such as square meters (m²), square feet (ft²), or square inches (in²).
When the vertical height is unknown, you can calculate area using Heron's Formula if all three side lengths (a, b, c) are known, or using Trigonometry A = ½ab sin(γ) if two sides and their enclosed angle are known.
A circle sector is a pie-shaped slice enclosed by two radii and an arc. An annulus is a ring-shaped region enclosed between two concentric circles with different radii.
For a regular polygon with n sides of length s, the area formula is A = (n × s²) / (4 × tan(π / n)).
Because exact ellipse perimeter involves complex elliptic integrals, Ramanujan's approximation is used: P ≈ π [3(a+b) - √((3a+b)(a+3b))].