Circle Calculator
Enter the radius of the circle to calculate other properties.
How to Use the Circle Calculator
Calculate Circle Properties
This calculator allows you to find the radius, diameter, circumference, and area of a circle based on one known value:
- Radius: The distance from the center to any point on the circle.
- Diameter: The distance across the circle through its center.
- Circumference: The distance around the circle.
- Area: The amount of space enclosed by the circle.
Step-by-Step Instructions
- Select the property you know (radius, diameter, circumference, or area).
- Enter the value in the input field.
- Choose the appropriate unit of measurement.
- Click the "Calculate" button.
- View the results for all circle properties.
Circle Formulas
Radius (r): The basic measure of a circle's size.
Diameter (d): d = 2r
Circumference (C): C = 2πr = πd
Area (A): A = πr²
Where π (pi) ≈ 3.14159...
Applications of Circle Calculations
Practical Applications
Circle calculations are used in many fields:
- Construction: Designing circular structures, pools, or landscape features.
- Engineering: Designing gears, wheels, and circular components.
- Physics: Calculating motion in circular paths.
- Everyday life: Determining the amount of material needed for circular objects like tables or rugs.
Example Calculations
Example 1: If a circle has a radius of 5 cm, its diameter is 10 cm, its circumference is approximately 31.42 cm, and its area is approximately 78.54 cm².
Example 2: If a circle has a diameter of 8 inches, its radius is 4 inches, its circumference is approximately 25.13 inches, and its area is approximately 50.27 square inches.
Example 3: If a circle has a circumference of 20 meters, its radius is approximately 3.18 meters, its diameter is approximately 6.37 meters, and its area is approximately 31.83 square meters.
FAQ
What is Pi (π)?
Pi (π) is the ratio of a circle's circumference to its diameter. It's approximately 3.14159, though this calculator uses the more precise value available in JavaScript's Math.PI constant.
How accurate are the calculations?
This calculator uses precise mathematical formulas and displays results rounded to 4 decimal places for readability. For most practical applications, this is more than sufficient accuracy.
Can I calculate the properties of a partial circle or arc?
This calculator is designed for complete circles. For calculations involving arcs or sectors, you would need the central angle in addition to one of the circle properties.
What units of measurement does this calculator support?
This calculator supports common length units (millimeters, centimeters, meters, inches, and feet). The area results will be in square units of the selected length unit.
Circle Conversion Table
| Radius (r) | Diameter (d) | Circumference (C) | Area (A) |
|---|---|---|---|
| 1 | 2 | 6.2832 | 3.1416 |
| 2 | 4 | 12.5664 | 12.5664 |
| 3 | 6 | 18.8496 | 28.2743 |
| 4 | 8 | 25.1327 | 50.2655 |
| 5 | 10 | 31.4159 | 78.5398 |
| 10 | 20 | 62.8319 | 314.1593 |