How to calculate centroid of a bounding box in Python OpenCV

Question

I am doing inference and detecting hands and I need to calculate the centroid of the bounding box of the detected hand.

Below is its coordinates:

left = 215 
bottom = 447 
right = 325 
top = 367

and this is how I am drawing the rectangle

cv2.rectangle(frame, (int(obj.Left), int(obj.Bottom)), (int(obj.Right), int(obj.Top)), (0, 0, 255), 2)

Now in order to calculate the centroid of the bounding box, I am using below lines of code:

w = int(obj.Right - obj.Left)
h = int(obj.Bottom - obj.Top)
cx = int(obj.Top + h/2)
cy = int(obj.Left + w/2)
print(cx, cy)

So first I am calculating the width and height of the bounding box. Then dividing the height and width by 2 and adding them to top and left respectively to calculate the centroid. But this doesn't seems to be working as you can see the white dot (represented in red circle) is far away from detected hand.

How can I improve it?