About the area calculator
Area measures the surface inside a flat shape, in square units. Pick a shape, enter its dimensions and the calculator returns the area, the perimeter or circumference where one exists, and conversions to square feet and square meters.
Formula
Rectangle = l × w. Triangle = ½ × b × h. Circle = π × r². Trapezoid = ½ × (a + b) × h. Parallelogram = b × h. Ellipse = π × a × b.
Frequently asked questions
How do I find the area of a circle?
Square the radius and multiply by π (3.14159). A circle with radius 5 has area 78.54.
What is the difference between area and perimeter?
Area is the space inside a shape (square units); perimeter is the distance around it (linear units).