If you need to solve some geometry exercises, this circumference calculator is the page for you. It is a tool specifically created to find the diameter, circumference and area of any circle. Read on to learn:

- What the definition of circumference is
- How to find the circumference of a circle
- How to convert circumference into diameter

As is the case with all of our tools, the circumference calculator works in all directions - it is also a circumference to diameter calculator, and can be used to convert circumference to radius, circumference to area, radius to circumference, radius to diameter (duh!), radius to area, diameter to circumference, diameter to radius (yes, again with the rocket science), diameter to area, area to circumference, area to diameter or area to radius.

If you want to draw a circle on the Cartesian plane, you might find this equation of a circle calculator useful.

## Definition of circumference

The circumference of a circle is the linear distance of a circle's edge. It is the same as the perimeter of a geometric figure, but the term 'perimeter' is used exclusively for polygons.

Circumference is often misspelled as *circumfrence*.

## Formula for circumference

The following equation describes the relation between the circumference and the radius `R`

of a circle:

`C = 2πR`

Where π is a constant approximately equal to 3.14159265...

💡 **It is impossible to find the exact value of π.** It is an irrational number, so we typically use approximations such as 3.14 or 22/7. If you're interested in this topic, go ahead and take a look at the first million digits of π.

A similarly simple formula determines the relationship between the area of a circle and its radius:

`A = π * R²`

## How to find the circumference of a circle

- Determine the radius of a circle. Let's assume it's equal to 14 cm.
- Substitute this value to the formula for circumference:
`C = 2 * π * R = 2 * π * 14 = 87.9646 cm`

. - You can also use it to find the area of a circle:
`A = π * R² = π * 14² = 615.752 cm²`

. - Finally, you can find the diameter - it is simply double the radius:
`D = 2 * R = 2 * 14 = 28 cm`

. - Use our circumference calculator to find the radius when you only have the circumference or area of a circle.

Circumference calculation is important for determining the hoop stress on any rotationally symmetrical object. Find out more with our hoop stress calculator.

## Circumference to diameter

You have probably noticed that, since diameter is twice the radius, the proportion between the circumference and the diameter is equal to π:

`C/D = 2πR / 2R = π`

This proportion (circumference to diameter) is the definition of the constant pi. It is used in many areas, such as physics and mathematics. For example, you can find it in the centrifugal force calculator.

🔎 If you're interested in the relationship between the circumference and other variables, you can take a look at our circumference to diameter and circumference and area of a circle calculators.

## FAQ

### How to find the circumference of a circle?

To calculate the circumference, you **need the radius of the circle**:

**Multiply**the radius by 2 to get the diameter.**Multiply**the result by π, or 3.14 for an estimation.- That's it; you found the
**circumference of the circle**.

Or you can use **the circle's diameter**:

**Multiply**the diameter by π, or 3.14.- The result is the
**circle's circumference**.

### What is the circumference of a circle?

The circumference of a circle is **the linear distance of the circle's edge**. It is equivalent to the **perimeter** of a geometric shape, although that term perimeter is only used for polygons.

### Who calculated the circumference of the earth first?

The **first person to calculate the Earth's circumference was Eratosthenes, a Greek mathematician**, in 240 B.C. He discovered that objects in a city on the Northern Tropic do not throw a shadow at noon on the summer solstice, but they do in a more northerly location. Knowing this, and the distance between the locations, he succeeded in calculating the Earth's circumference.

### How do I find the diameter from the circumference?

If you want to **find the diameter from the circumference of a circle**, follow these steps:

**Divide**the circumference by π, or 3.14 for an estimation.- And that's it;
**you have the circle's diameter**.

### How to find the area of a circle from the circumference?

To **find the area of a circle from the circumference**, follow these steps:

**Divide**the circumference by π.**Divide**the result by 2 to get the**circle's radius**.**Multiply**the radius by itself to get its square.**Multiply**the square by π, or 3.14 for an estimation.- You found the
**circle's area from the circumference**.

### How do I find the radius from the circumference?

To **find the radius from the circumference of a circle**, you have to do the following:

**Divide**the circumference by π, or 3.14 for an estimation. The result is the circle's diameter.**Divide**the diameter by 2.- There you go,
**you found the circle's radius**.

### How to measure the circumference?

- Calculate the circumference as
**2 ⨉ radius ⨉ π**. - Calculate the circumference as
**diameter ⨉ π**. - Wrap a
**string around the object**and measure the length of it. - Use
**Omni's circumference calculator**.

### What is the formula for the circumference?

The **formula for the circumference**, if the circle's radius is given, is:

**2 ⨉ radius ⨉ π**

Or if the circle's circumference is given:

**Circumference ⨉ π**

You can estimate π as 3.14.

### What is the circumference of a circle with a radius of 1 meter?

To **calculate the circumference of a circle with a radius of 1 meter**, simply follow these steps:

**Multiply**the radius by 2 to get the diameter of 2 meters.**Multiply**the result by π, or 3.14 for an estimation.- And there you go; the
**circumference of a circle with a radius of 1 meter is 6.28 meters**.

### How do I find the circumference of a cylinder?

To **find the circumference of a cylinder**, you have to be aware that a cylinder's cross-section is a circle. If you know the cylinder's radius:

**Multiply**the radius by 2 to get the diameter.**Multiply**the result by π, or 3.14 for an estimation.- That's it; you found the
**circumference of the cylinder**.

Or you can use **the cylinder's diameter**:

**Multiply**the diameter by π, or 3.14.- The result is the
**cylinder's circumference**.

### How do I find the area of a circle with a circumference of 1 meter?

If you want to **find the area of a circle with a circumference of 1 meter**, do the following:

**Divide**the circumference by π. This is the**circle's diameter**, in this case, 31.8 centimeters.**Divide**by 2. This result is the**circle's radius**of 15.9 centimeters.**Multiply**the radius with itself, getting the square, in our case 256 cm².**Multiply**by π, or 3.14 for an estimation.- That's it;
**a circle with a circumference of 1 meter has an area of 795.78 cm²**.

### How to find the radius of a circle with a circumference of 10 centimeters?

To **find the radius of a circle with a circumference of 10 centimeters**, you have to do the following:

**Divide**the circumference by π, or 3.14 for an estimation. The result is the circle's diameter, 3.18 centimeters.**Divide**the diameter by 2.- And there you go,
**the radius of a circle with a circumference of 10 centimeters is 1.59 centimeters**.

### What is the unit of the circumference of a circle?

Since a circle's circumference is the linear distance of the circle's edge, it describes a length. Therefore, the **most common units of a circle's circumference are millimeter, centimeter, meter for the metric system, and inch, feet, and yard for the imperial system**.