# backgroundSize

> Background image size value. Transitions are fully supported only when using size in pixels or percentages, such as pixel-to-pixel or percentage-to-percentage transitions.

## Definition

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

```csharp
BackgroundSize backgroundSize { get; }
```