---
title: "lerp"
description: "Linearly interpolate between two radii.

The [fraction] argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning [start] (or something equivalent to [start]), 1.0
meaning that the interpolation has finished, returning [stop] (or something equivalent to
[stop]), and values in between meaning that the interpolation is at the relevant point on the
timeline between [start] and [stop]. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for [fraction] are usually obtained from an [Animation<Float>], such as an
`AnimationController`."
type: "function"
---

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


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


```kotlin
fun lerp(start: CornerRadius, stop: CornerRadius, fraction: Float): CornerRadius
```


Linearly interpolate between two radii.

The `fraction` argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning `start` (or something equivalent to `start`), 1.0
meaning that the interpolation has finished, returning `stop` (or something equivalent to
`stop`), and values in between meaning that the interpolation is at the relevant point on the
timeline between `start` and `stop`. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for `fraction` are usually obtained from an `Animation<Float>`, such as an
`AnimationController`.



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


```kotlin
fun lerp(start: RoundRect, stop: RoundRect, fraction: Float): RoundRect
```


Linearly interpolate between two rounded rectangles.

The `fraction` argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning `start` (or something equivalent to `start`), 1.0
meaning that the interpolation has finished, returning `stop` (or something equivalent to
`stop`), and values in between meaning that the interpolation is at the relevant point on the
timeline between `start` and `stop`. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for `fraction` are usually obtained from an `Animation<Float>`, such as an
`AnimationController`.



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


```kotlin
fun lerp(start: Rect, stop: Rect, fraction: Float): Rect
```


Linearly interpolate between two rectangles.

The `fraction` argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning `start` (or something equivalent to `start`), 1.0
meaning that the interpolation has finished, returning `stop` (or something equivalent to
`stop`), and values in between meaning that the interpolation is at the relevant point on the
timeline between `start` and `stop`. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for `fraction` are usually obtained from an `Animation<Float>`, such as an
`AnimationController`.



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


```kotlin
fun lerp(start: Size, stop: Size, fraction: Float): Size
```


Linearly interpolate between two sizes

The `fraction` argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning `start` (or something equivalent to `start`), 1.0
meaning that the interpolation has finished, returning `stop` (or something equivalent to
`stop`), and values in between meaning that the interpolation is at the relevant point on the
timeline between `start` and `stop`. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for `fraction` are usually obtained from an `Animation<Float>`, such as an
`AnimationController`.



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


```kotlin
fun lerp(start: Offset, stop: Offset, fraction: Float): Offset
```


Linearly interpolate between two offsets.

The `fraction` argument represents position on the timeline, with 0.0 meaning that the
interpolation has not started, returning `start` (or something equivalent to `start`), 1.0
meaning that the interpolation has finished, returning `stop` (or something equivalent to
`stop`), and values in between meaning that the interpolation is at the relevant point on the
timeline between `start` and `stop`. The interpolation can be extrapolated beyond 0.0 and 1.0, so
negative values and values greater than 1.0 are valid (and can easily be generated by curves).

Values for `fraction` are usually obtained from an `Animation<Float>`, such as an
`AnimationController`.