Version: 2017.2
public static float InverseLerp (float a, float b, float value);


Calculates the linear parameter t that produces the interpolant value within the range [a, b].

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public float walkSpeed = 5.0F; public float runSpeed = 10.0F; public float speed = 8.0F; void Start() { float parameter = Mathf.InverseLerp(walkSpeed, runSpeed, speed); } }

See Also: Lerp.