Scale Property
The zoom scale resulting from the pinch gesture. This number is the ratio between the distance between the fingers at the end of the pinch gesture to the distance between the fingers at the beginning of the pinch gesture.

For example, if you were to touch a screen with your fingers 6 cm apart, and pinch until your fingers were 3 cm apart, the scale would be 0.5. Likewise, if your fingers were 3 cm apart, and you pinch until your fingers are 6 cm apart, the scale would be 2.

C# Syntax
public double Scale {get; set;}