Calculate the Capacitance of Nearly Spherical Surface Area

The simple online calculator which is used to calculate the capacitance of nearly spherical surface area based on Relative Permittivity (εr), and Area.
Formula: C ≃ 3.139*10-11εrS1/2
Where, C = Capacitance of Spherical Surface, S = Area, εr = Relative Permittivity
Relative Permittivity (εr): 
Capacitance of Spherical Surface: F