# PI

> The well-known 3.14159265358979... value (Read Only).

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
public const float PI = 3.1415927
```

### Remarks

The ratio of the circumference of a circle to its diameter. Note that this value is a 32-bit floating point number i.e. a float.  Approximately seven digits of precision are provided.

### Examples

```csharp
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public float radius = 5;

    void Start()
    {
        float perimeter = 2.0f * Mathf.PI * radius;
        Debug.Log("The perimeter of the circle is: " + perimeter);
    }
}
```