Area Calculator
Area: 0
How Each Shape's Area Is Calculated
Area is the amount of two-dimensional space a shape encloses, and each shape has its own standard formula: a square is side², a rectangle is length × width, a triangle is ½ × base × height, a circle is πr², a trapezoid is ½ × (base A + base B) × height, an ellipse is π × a × b, a parallelogram is base × height, and a circular sector is the fraction of the circle's area swept by its angle: (θ/360) × πr². This calculator applies the correct formula automatically based on the shape you pick.
Area vs. Perimeter — Don't Confuse Them
Area measures the surface enclosed by a shape (in square units, like ft² or m²), while perimeter (or circumference for a circle/ellipse) measures the total length of its boundary (in linear units). Two shapes can have the same area but very different perimeters, or vice versa — a long thin rectangle and a square can enclose the same area while having very different amounts of edge. This calculator reports both figures side by side so you can see the relationship for your specific dimensions.
Working With Triangles and Circles
If you only know a triangle's three side lengths rather than its base and height, use the triangle calculator to find its area directly via Heron's formula. For questions about a circle's radius, diameter, or circumference individually, the circle calculator breaks those out in more detail.
Frequently Asked Questions
Which formula does the area calculator use for each shape?
It uses the standard geometric formula for whichever shape you select: side squared for a square, length times width for a rectangle, half times base times height for a triangle, pi r squared for a circle, half times (base A + base B) times height for a trapezoid, pi times a times b for an ellipse, base times height for a parallelogram, and (angle/360) times pi r squared for a circular sector.
Why does the calculator sometimes show perimeter as not applicable?
Triangle, trapezoid, and parallelogram area only require a base and height, which isn't enough information to determine the perimeter (you'd also need the side lengths or angles). For those shapes the calculator focuses on area only; use the triangle calculator if you have all three side lengths and want its perimeter too.