Blog
Clear, math-first articles for curious minds.
Circumference vs. Perimeter: What's the Difference?
Circumference and perimeter both measure the distance around a shape. Here's the simple difference, when to use each word, and how to calculate both.
How to Find the Diameter From the Circumference
Reverse the circle formula to find diameter from circumference. The simple equation, worked examples, and a free calculator to do it instantly.
How to Calculate the Circumference of a Circle (4 Simple Methods)
Find the circumference of any circle from its radius, diameter, or area. Clear formulas, step-by-step worked examples, and a free calculator to check your answer.
How to Find the Area of a Circle (Formula + Examples)
How to find the area of a circle using A = πr². Simple steps and worked examples for finding the area from the radius, diameter, or circumference — plus a free calculator.
How to Find the Radius From the Circumference (With Examples)
How to find the radius from the circumference using r = C ÷ (2π). Simple steps and worked examples, plus a free calculator that does it instantly.
Radius vs Diameter: What's the Difference?
The difference between the radius and diameter of a circle, how to convert between them, and simple examples. Plus a free calculator for radius, diameter, circumference, and area.
The Circumference Formula Explained: Where C = 2πr Actually Comes From
A clear, illustrated explanation of the circumference formula, the role of π, three common variations, and how to use the formula in real-world problems.