# deltaTime

> The interval in seconds from the last frame to the current one (Read Only).

## Definition

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

```csharp
public static float deltaTime { get; }
```

### Remarks

When this is called from inside [MonoBehaviour.FixedUpdate()](/engine/6000.0/script-reference/unityengine/monobehaviour/fixedupdate.md), it returns [Time.fixedDeltaTime](/engine/6000.0/script-reference/unityengine/time/fixeddeltatime.md). The maximum value for `deltaTime` is defined by [Time.maximumDeltaTime](/engine/6000.0/script-reference/unityengine/time/maximumdeltatime.md).

`deltaTime` inside [MonoBehaviour.OnGUI()](/engine/6000.0/script-reference/unityengine/monobehaviour/ongui.md) is not reliable, because Unity might call it multiple times per frame.

The following example rotates a GameObject around its z axis at a constant speed.

See [Time and Frame Rate Management](/engine/6000.0/manual/scripting/object-oriented-development/managing-time-and-frame-rate.md) in the User Manual for more information about how this property relates to the other Time properties.

```csharp
using UnityEngine;
// Rotate around the z axis at a constant speed
public class ConstantRotation : MonoBehaviour
{
    public float degreesPerSecond = 2.0f;
    void Update()
    {
        transform.Rotate(0, 0, degreesPerSecond * Time.deltaTime);
    }
}
```

The following example implements a timer. The timer adds deltaTime each frame. The example displays the timer value and resets it when it reaches 2 seconds. [Time.timeScale](/engine/6000.0/script-reference/unityengine/time/timescale.md) controls the speed at which time passes and how fast the timer resets.

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

// Time.deltaTime example.
//
// Wait two seconds and display waited time.
// This is typically just beyond 2 seconds.
// Allow the speed of the time to be increased or decreased.
// It can range between 0.5 and 2.0. These changes only
// happen when the timer restarts.

public class ScriptExample : MonoBehaviour
{
    private float waitTime = 2.0f;
    private float timer = 0.0f;
    private float visualTime = 0.0f;
    private int width, height;
    private float value = 10.0f;
    private float scrollBar = 1.0f;

    void Awake()
    {
        width = Screen.width;
        height = Screen.height;
        Time.timeScale = scrollBar;
    }

    void Update()
    {
        timer += Time.deltaTime;

        // Check if we have reached beyond 2 seconds.
        // Subtracting two is more accurate over time than resetting to zero.
        if (timer > waitTime)
        {
            visualTime = timer;

            // Remove the recorded 2 seconds.
            timer = timer - waitTime;
            Time.timeScale = scrollBar;
        }
    }

    void OnGUI()
    {
        GUIStyle sliderDetails = new GUIStyle(GUI.skin.GetStyle("horizontalSlider"));
        GUIStyle sliderThumbDetails = new GUIStyle(GUI.skin.GetStyle("horizontalSliderThumb"));
        GUIStyle labelDetails = new GUIStyle(GUI.skin.GetStyle("label"));

        // Set the size of the fonts and the width/height of the slider.
        labelDetails.fontSize = 6 * (width / 200);
        sliderDetails.fixedHeight = height / 32;
        sliderDetails.fontSize = 12 * (width / 200);
        sliderThumbDetails.fixedHeight = height / 32;
        sliderThumbDetails.fixedWidth = width / 32;

        // Show the slider. Make the scale to be ten times bigger than the needed size.
        value = GUI.HorizontalSlider(new Rect(width / 8, height / 4, width - (4 * width / 8), height - (2 * height / 4)),
            value, 5.0f, 20.0f, sliderDetails, sliderThumbDetails);

        // Show the value from the slider. Make sure that 0.5, 0.6... 1.9, 2.0 are shown.
        float v = ((float)Mathf.RoundToInt(value)) / 10.0f;
        GUI.Label(new Rect(width / 8, height / 3.25f, width - (2 * width / 8), height - (2 * height / 4)),
            "timeScale: " + v.ToString("f1"), labelDetails);
        scrollBar = v;

        // Display the recorded time in a certain size.
        labelDetails.fontSize = 14 * (width / 200);
        GUI.Label(new Rect(width / 8, height / 2, width - (2 * width / 8), height - (2 * height / 4)),
            "Timer value is: " + visualTime.ToString("f4") + " seconds.", labelDetails);
    }
}
```