Coordinates of center of circles

I need to change the position of circles on a web app during runtime by changing their centers coordinates. The coordinates (x y) of the circles are with respect to the top left. How can I use their center point coordinates? Can someone help me?

g.DrawOval (x, y, width, height)


Should be simple math.
x = centerX - width/2
y = centerY - height/2


Center of circle on X axis = x + (width/2)
Center of circle on Y axis = y + (height/2)

Thanks tim