Geometry Calculator
A geometry calculator finds a 2D shape’s area and perimeter (or circumference for a circle) from a few measurements. Toolverge covers the four most-searched shapes — circle, square, rectangle, and triangle — using radius, side length, or Heron’s formula for a triangle’s three sides, so you never need to remember which formula applies to which shape.
How it works
- Choose a shape: circle, square, rectangle, or triangle.
- Enter its dimensions (radius, side, or three side lengths).
- Read the area and perimeter/circumference on the tape.
Formula Circle: A=πr², C=2πr · Square: A=s², P=4s · Rectangle: A=lw, P=2(l+w) · Triangle (Heron’s): s=(a+b+c)/2, A=√(s(s-a)(s-b)(s-c))
Frequently asked questions
How do I find the area of a circle?
Multiply pi (π ≈ 3.14159) by the radius squared: A = πr².
How does the triangle mode work without a height?
It uses Heron’s formula, which finds area from the three side lengths alone (via the semi-perimeter s), so you don’t need to know the triangle’s height.
Why does the triangle sometimes show no result?
The three side lengths must satisfy the triangle inequality — each side shorter than the sum of the other two — or no such triangle exists.
Can I calculate a square as a special rectangle?
Yes — enter the same value for both length and width in Rectangle mode, or use Square mode directly.
Does this cover 3D shapes like a sphere or cube?
No — that’s the separate Volume Calculator, which covers cube, sphere, and cylinder volume and surface area.