You can either measure it, or calculate it if you know the diameter (radius = diameter / 2), or the circumference (radius = circumference / (2pi)).
Chat with our AI personalities
The longest chord in a circle is its diameter and halve of this is its radius.
Measure the diametre of the circle and divide by two to give the radius.
The diameter is the length of a line touching both sides of the circle and passing through the centre. The radius is the length of a line from the centre to touching the circle, and is half the length of the diameter, the diameter then is twice the length of the radius > diameter = radius * 2 = 32 * 2 = 64
The radius of a circle is the length of the line from the center of the circle to any point on its edge.
The radius of a circle is the distance from its centre to its circumference. If a circle has a radius of r units then the length of its circumference is 2*pi*r units.