how does diopters "close up filters" affects depth of field

[Abdul Rahman Jamous]

Greetings my awesome fellows, hope everyone is doing FANTASTIC!

 

let's say that the focus of the lens I'm using is set 2 meters away from the camera. If I used a diopter ( strength  +1/8 or +1 ), naturally the depth of field will shift closer to the camera. my question is how to calculate that shift???