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2D Geometric Area & Perimeter Calculator

Compute surface area and boundary perimeter for all standard 2D geometric shapes.

Quick Answer:Select a 2D shape, enter its dimensions (radius, length, height, or axes), and instantly receive the total area and perimeter.

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How to Use the Area Calculator: 2D Shapes, Rectangles & Circles

1Select your desired shape (rectangle, circle, triangle, trapezoid, or ellipse).
2Enter the requested dimensional measurements (e.g. width, height, radius).
3Instantly view the calculated square surface area and exterior perimeter.
4Use the results for floor planning, turf installation, or geometric problem solving.

Rectangle: A = l × w; Circle: A = πr²; Triangle: A = ½bh; Ellipse: A = πab

Applies standard Euclidean geometry equations including Ramanujan approximation for ellipses.

Input: Length: 15, Width: 12

Explanation: 15 × 12 = 180 square feet; 2 × (15 + 12) = 54 linear feet perimeter.

Result: Area: 180 sq ft, Perimeter: 54 ft

What is the difference between area and perimeter?▼

Area measures the two-dimensional surface space inside a shape, while perimeter measures the total linear distance around the outside boundary.

How do you calculate the area of an irregular shape?▼

Decompose the irregular shape into basic rectangles, triangles, and circles, compute each individual area, and sum them together.

Can this calculator compute land acreage?▼

Yes, calculate square footage first and divide by 43,560 to convert the area to standard acres.

How do you find circle area from diameter?▼

Divide the diameter by 2 to find the radius (r), then square that radius and multiply by π (A = π(d/2)²).

Shape	Area Formula	Perimeter Formula	Key Parameters
Rectangle	l × w	2(l + w)	Length, Width
Circle	πr²	2πr	Radius
Triangle	½ × b × h	a + b + c	Base, Height
Ellipse	π × a × b	π[3(a+b) - √((3a+b)(a+3b))]	Semi-axes a, b