So if you have a single inductor then I assume that there is no flux linkage and that L = flux*N / i = L11 and so that flux is total leakage flux. If you have two inductors then the flux leakage is any flux that isn't flux linkage (the self flux is flux leakage). (flux21 is the flux in 2 from 1, flux11 is the flux in 1 from 1 etc.) According to my book the coupling coefficients are: k1 = flux21/flux11 k2 = flux12/flux22 k = sqrt(k1*k2) And mutual inductance = L12 = L21 = k*sqrt(L11*L22) What I'm wondering is that how do you calculate flux12 or flux 21? And that value for inductance of: N2/reluctance is that the total inductance of L11 + L12 ? And if you have two inductors how do you calculate flux11 and flux22 and their respective linkages? If you have a transformer can you say inductance of side one is: L = NBA/i (where N is turns of that side, i is current of that side and BA is the flux going through that side) Is that the total inductance given to you by that formula, L11 + L12 and how do you calculate wich is wich flux, like what the leakage flux is? Cheers in advance!