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Circumference Calculator

Calculate the circumference of a circle using radius or diameter. Get precise results with multiple unit options and detailed explanations.

📐 Formulas & Explanations

🔢 Mathematical Formulas

C = 2πr
Circumference from radius
C = πd
Circumference from diameter
A = πr²
Area of circle

🌍 Real-world Examples

Coin (Quarter) ~7.5 cm circumference
Basketball ~75 cm circumference
Car Tire ~2 m circumference
Earth's Equator ~40,075 km circumference

✨ Features

🎯

High Precision

Uses precise π value for accurate calculations with proper rounding

🔄

Dual Input Methods

Calculate from radius or diameter with automatic conversions

📏

Multiple Units

Support for metric and imperial units with instant conversion