Formula Radius of Circle & Diameter Calculator
Fast, interactive diameter area calculator and geometric guide. Learn the formula radius of circle, master the diameter of a circle formula, apply the circular diameter formula, and discover how to work out area of a circle using diameter.
Circle Dimension Calculator & Equation Solver
Enter any one known dimension to instantly compute all other circular properties.
A = (π × d²) / 4
Circle Radius & Diameter Mathematical Guide
What is the formula radius of circle?
The formula radius of circle depends on which dimension you know: from diameter ($r = d / 2$), from circumference ($r = C / (2\pi)$), or from area ($r = \sqrt{A / \pi}$). The radius is always the distance from the exact center to any point on the outer circumference.
What is the diameter of a circle formula?
The diameter of a circle formula (and circular diameter formula) is the straight line distance passing through the center connecting two boundary points: d = 2r. When solving what is the formula to find diameter of a circle from circumference, use d = C / \pi, and the formula for calculating diameter of a circle from area is d = 2 \times \sqrt{A / \pi}.
How to work out area of a circle using diameter?
To learn how to work out area of a circle using diameter with our area of circle equation diameter: substitute $r = d / 2$ into $A = \pi r^2$, giving A = \frac{\pi d^2}{4}. For instance, if a circle has a diameter of $10\text{ cm}$, $A = \frac{\pi \times 100}{4} = 25\pi \approx 78.54\text{ cm}^2$.
How to find the dimensions of a circle from any known value?
To discover how to find the dimensions of a circle using our equation to find the diameter of a circle and circle diameter to area calculator: simply enter any one parameter. Since $\pi \approx 3.14159265$ is constant, all 4 circular dimensions are mathematically locked and can be calculated instantaneously.