Area Calculator

This finds the area of a flat shape: a rectangle or square, a triangle from base and height, a circle, a trapezoid, a parallelogram, an ellipse, and any regular polygon from three sides upwards. Enter the lengths in meters, centimeters, feet, inches or yards and it returns the area in that unit squared, converted again into square meters and square feet, with the perimeter wherever the inputs are enough to fix it. Nothing here is three dimensional, so volume, surface area and the floor area of a house belong to other tools. The one figure that is not exact is the ellipse perimeter, which uses the Ramanujan approximation because no simple formula gives it exactly.