Enter values and select Calculate.
Calculated result
Area formulas
- Rectangle: A = length × width
- Square: A = side²
- Triangle: A = base × perpendicular height ÷ 2
- Circle: A = π × radius²
- Parallelogram: A = base × perpendicular height
- Trapezoid: A = (base a + base b) × perpendicular height ÷ 2
How to calculate area
Select the shape, enter the dimensions required by that shape, and keep every dimension in the same unit. The calculator applies the matching formula and reports the result in squared units.
Area calculator examples
Rectangle: lw. Square: s². Triangle: bh÷2. Circle: πr². Parallelogram: bh. Trapezoid: (a+b)h÷2.
A 10 by 5 rectangle has area 50 square units. A circle with radius 5 has area 25π, approximately 78.5398 square units.
Calculations retain floating-point precision and use controlled display formatting. Decimal results involving π are approximations.
Supported shapes
Rectangle and square cover right-angled four-sided figures.
Triangle and parallelogram use perpendicular height.
Trapezoid uses the two parallel bases and their perpendicular height.
Circle uses radius, not diameter.
Area versus square footage
This page owns general geometric area across multiple shapes.
Use Square Footage Calculator for practical rectangular sections and a square-foot-first result.
Shape modes stay on this one canonical rather than creating separate thin pages.
Area units
Area is expressed in square units, never ordinary linear units.
Unit conversion squares the underlying length factor.
π-based decimal values are rounded displays, while calculations retain full floating-point precision.
Methodology and limits
Formulas are standard Euclidean geometry. Length conversions follow exact defined factors, including 1 inch = 0.0254 meter; area factors are squared and volume factors are cubed. This browser-local tool does not evaluate expressions or infer real-world material needs.