For an isolated conducting sphere, it is simply equal to R.
For two touching conducting spheres of radius R, it is equal to 2R log 2.  For an isolated conducting sphere, it is simply equal to R. Both of these are expressed in Gaussian units and measured relative to infinity.  More commonly, the geometry is such that two separated conductors carry opposite charges and it can be increased by a factor of the dielectric constant.  Defined as charge stored per unit of potential difference, FTP, what is this physical quantity which measures the ability to store electrical energy, whose SI unit is farads?
For two touching conducting spheres of radius R, it is equal to 2R log 2.  
capacitance