Home › API Reference › Time

Time

Type	Class (static members)
Namespace	`UnityEngine`

Time

The Time class tells you how much time has passed: since the last frame, since the game started, and at what speed the game is running. It's the key to making things move at the same speed on every computer.

Frames are like the steps you take while walking. A fast computer takes many small steps per second; a slow one takes fewer, bigger steps. Time.deltaTime is the length of your last step in seconds. Multiply your speed by it and you cover the same distance per second no matter how many steps you take.

Static Properties

Name	Type	Description
`deltaTime`	`float`	Seconds since the last frame (e.g. 0.016 at 60 FPS). Multiply movement by this. Inside `FixedUpdate` it returns `fixedDeltaTime`.
`fixedDeltaTime`	`float`	Seconds between physics steps. Default 0.02 (50 per second).
`time`	`float`	Seconds since the game started (scaled by `timeScale`). Good for cooldowns.
`timeScale`	`float`	Game speed. 1 = normal, 0.5 = slow motion, 0 = paused.
`unscaledDeltaTime`	`float`	Like `deltaTime` but ignores `timeScale`. Use for pause menus and UI.
`unscaledTime`	`float`	Like `time` but ignores `timeScale`.
`realtimeSinceStartup`	`float`	Real seconds since the app launched. Keeps counting even when paused.
`frameCount`	`int`	How many frames have been started.

Code Samples

Frame-rate independent movement

// BAD: moves 0.1 units per frame. 60 FPS = 6 units/s, 144 FPS = 14.4 units/s.
transform.position += Vector3.forward * 0.1f;

// GOOD: moves 5 units per second on every machine.
transform.position += Vector3.forward * 5f * Time.deltaTime;

A cooldown timer

using UnityEngine;

public class Dash : MonoBehaviour
{
    [SerializeField] private float cooldown = 2f;
    private float readyAt;

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.LeftShift) && Time.time >= readyAt)
        {
            Debug.Log("Dash!");
            readyAt = Time.time + cooldown;
        }
    }
}

Pause and slow motion

public void Pause()      { Time.timeScale = 0f; }
public void Resume()     { Time.timeScale = 1f; }
public void SlowMotion() { Time.timeScale = 0.3f; }

UI that still animates while paused

void Update()
{
    // Spins even when Time.timeScale is 0.
    loadingIcon.Rotate(0f, 0f, -180f * Time.unscaledDeltaTime);
}

What happens at runtime

When you set timeScale = 0:

Time.deltaTime becomes 0, so anything multiplied by it stops moving.
Time.time stops increasing, so cooldowns freeze.
FixedUpdate stops being called, so physics freezes.
Animators (in Normal update mode) freeze. WaitForSeconds never finishes.
Update still runs every frame. Input still works, which is how you can un-pause.

Common Mistakes

Forgetting deltaTime in Update movement, or using it where you shouldn't: rb.linearVelocity = dir * speed is already "per second", so don't multiply velocity by deltaTime.
Thinking timeScale 0 stops everything. Your own Update code that doesn't use deltaTime keeps running.
Forgetting to reset timeScale when loading a new scene from a pause menu. It stays at 0 and the new scene is frozen.
Slow motion looks choppy? Physics still steps every 0.02 game seconds, so it steps less often in real time. Also scale Time.fixedDeltaTime by the same factor, or enable Interpolate on Rigidbodies.

Time

Static Properties

Code Samples

Frame-rate independent movement

A cooldown timer

Pause and slow motion

UI that still animates while paused

What happens at runtime

Common Mistakes

See also