---
title: "derivedStateOf"
description: "Creates a [State] object whose [State.value] is the result of [calculation]. The result of
calculation will be cached in such a way that calling [State.value] repeatedly will not cause
[calculation] to be executed multiple times, but reading [State.value] will cause all [State]
objects that got read during the [calculation] to be read in the current [Snapshot], meaning that
this will correctly subscribe to the derived state objects if the value is being read in an
observed context such as a [Composable] function. Derived states without mutation policy trigger
updates on each dependency change. To avoid invalidation on update, provide suitable
[SnapshotMutationPolicy] through [derivedStateOf] overload."
type: "function"
---

<div class='type'>Function</div>


<a id='references'></a>
<div class='sourceset sourceset-common'>Common</div>


```kotlin
@StateFactoryMarker
public fun <T> derivedStateOf(calculation: () -> T): State<T>
```


Creates a `State` object whose `State.value` is the result of `calculation`. The result of
calculation will be cached in such a way that calling `State.value` repeatedly will not cause
`calculation` to be executed multiple times, but reading `State.value` will cause all `State`
objects that got read during the `calculation` to be read in the current `Snapshot`, meaning that
this will correctly subscribe to the derived state objects if the value is being read in an
observed context such as a `Composable` function. Derived states without mutation policy trigger
updates on each dependency change. To avoid invalidation on update, provide suitable
`SnapshotMutationPolicy` through `derivedStateOf` overload.

#### Parameters

| | |
| --- | --- |
| calculation | the calculation to create the value this state object represents. |




<div class='sourceset sourceset-common'>Common</div>


```kotlin
@StateFactoryMarker
public fun <T> derivedStateOf(policy: SnapshotMutationPolicy<T>, calculation: () -> T): State<T>
```


Creates a `State` object whose `State.value` is the result of `calculation`. The result of
calculation will be cached in such a way that calling `State.value` repeatedly will not cause
`calculation` to be executed multiple times, but reading `State.value` will cause all `State`
objects that got read during the `calculation` to be read in the current `Snapshot`, meaning that
this will correctly subscribe to the derived state objects if the value is being read in an
observed context such as a `Composable` function.

#### Parameters

| | |
| --- | --- |
| policy | mutation policy to control when changes to the `calculation` result trigger update. |
| calculation | the calculation to create the value this state object represents. |




## Code Examples
### DerivedStateSample
```kotlin
@Suppress("CanBeVal", "unused")
@Composable
fun DerivedStateSample() {
    @Composable
    fun CountDisplay(count: State<Int>) {
        Text("Count: ${count.value}")
    }
    @Composable
    fun Example() {
        var a by remember { mutableStateOf(0) }
        var b by remember { mutableStateOf(0) }
        val sum = remember { derivedStateOf { a + b } }
        // Changing either a or b will cause CountDisplay to recompose but not trigger Example
        // to recompose.
        CountDisplay(sum)
    }
}
```