The Area Calculator computes the area of rectangles, circles, triangles, and trapezoids — showing the formula used and the result in square units.

How to Use This Calculator

1. Click a shape tab: Rectangle, Circle, Triangle, or Trapezoid.
2. Enter the required dimensions.
3. Click Calculate Area.

Area Formulas Quick Reference

• Rectangle: A = length × width
• Circle: A = π × radius² ≈ 3.14159 × r²
• Triangle: A = ½ × base × height (where height is perpendicular to the base)
• Trapezoid: A = ½ × (base₁ + base₂) × height

Real-World Applications

Home improvement: Calculate how much flooring, paint, or turf you need. Paint typically covers 350–400 sq ft per gallon; knowing your wall area prevents over- or under-buying.

Gardening: Find how much soil, fertilizer, or seed to buy. Products are sold per square foot or square meter.

Construction: Estimate roofing materials, concrete pads, or tile quantities. Always add 10–15% for waste and cuts.

Land measurement: Convert area to acres (1 acre = 43,560 sq ft) or hectares (1 hectare = 10,000 m²).

Frequently Asked Questions

What unit is the result in?

The result is in whatever unit you use for the inputs, squared. If you enter meters, the result is m². If you enter feet, the result is ft². There is no unit conversion — enter all dimensions in the same unit.

How do I find the height of a triangle if I only know the three sides?

Use Heron’s formula: s = (a+b+c)/2; Area = √(s(s−a)(s−b)(s−c)). You can rearrange to height = 2×Area/base once you have the area.