Geometry is the area of mathematics that studies shapes, sizes, relative position of figures, and properties of space. It covers 2D figures like triangles and circles and 3D solids like cylinders and spheres.

How do I find area and perimeter?

Each shape has its own formula. For example, rectangle area = length × width, circle area = πr², triangle area = 1/2 × base × height. This page provides calculators and formulas for the most common shapes.

What is the difference between 2D and 3D geometry?

2D geometry deals with flat shapes and measures area and perimeter, while 3D geometry deals with solids and measures volume and surface area.

Geometry | Shape Area, Perimeter & Volume Calculators

1. Choose a shape

Common geometry formulas

2D shapes

Rectangle: Area = l × w, Perimeter = 2(l + w)

Triangle (base-height): Area = ½ × b × h

Circle: Area = πr², Circumference = 2πr

Trapezoid: Area = ½ × (b₁ + b₂) × h

3D solids

Sphere: Volume = 4/3 πr³, Surface area = 4πr²

Cylinder: Volume = πr²h, Surface area = 2πr(h + r)

Cone: Volume = ⅓ πr²h, Surface area = πr(r + s) where s = √(r² + h²)

Tips

Always use the same unit for every measurement (all in cm, or all in m).
Area is squared units (cm², m²), volume is cubic units (cm³, m³).
Circles and spheres always bring in π — leave it as π or round to 3.14159.

FAQ

Can i use this for homework?

Yes — the calculator shows the same formulas you see in school. You can copy the numbers in and round to the required decimal places.

What if a triangle is not right or i only know the sides?

Use Heron’s formula: Area = √(s(s − a)(s − b)(s − c)) where s = (a + b + c)/2. For brevity the interactive calculator above uses base and height, but you can extend it with Heron easily.

Geometry