Home / Geometry Calculator
Geometry Calculator
This free geometry calculator works out area and perimeter (and related measurements like diagonal, circumference, or hypotenuse) for the seven shapes people look up most: circle, rectangle, square, triangle, trapezium, parallelogram and rhombus. For triangles, it uses Heron's formula when you know all three sides. It's handy for schoolwork, flooring or tiling estimates, land measurement, or general DIY calculations.
Geometry Calculator
Area and perimeter for the shapes people look up most.
Also known as: area calculator, perimeter calculator, circle/triangle/rectangle area calculator, square footage calculator.
FAQ
How do I calculate the area of a triangle from three sides?
Use Heron's formula: find the semi-perimeter s = (a+b+c)/2, then area = √(s(s−a)(s−b)(s−c)). The triangle tab above does this automatically.
What is the formula for circle area?
Area = π × radius². The calculator also gives circumference, diameter, and optional arc/sector calculations.