Dear all, I would like to estimate the inductance of a rather arbitrarily shaped coil composed of multiple single loops. For example, I am wondering about the inductance of sandglass like coil which has many turns at the edge and less in the middle. The inductance of a single loop seems to be well-known. How can I find out the inductance of a coil composed of these single loops? Would it be just a simple sum of them? Do I need to consider the mutual inductance between single loops as well? Thank you in advance.