Capacitance per centimeter
So, I wonder do I need to consider that per cm here when I am
designing it and get rid of it or should I assume to design a 1pf
capacitor means 1pf/cm.

It's likely that the math behind the calculator is approximating the interdigital capacitance by straightening out the interleaved fingers and treating the &quot;problem&quot; as a 2D problem i.e. it is working out the capacitance between two parallel planar electrodes such as in this QuickField article on calculating interdigital capacitance: -

So, when the wireless world calculator talks about capacitance per cm, the &quot;per cm&quot; refers to the length of the line snaking through the mid position between the two electrodes in the picture above.