How to calculate the flux linkage of a permanent magnet?

Question

Physics

How to calculate the flux linkage of a permanent magnet?
or the flux of permanent magnets

is known:
the residual magnetic permeability of the magnets, the dimensions of the magnets
is a motor rotor with two pairs of poles

, judging by the units of measurement, in order to obtain the rotor flux linkage (Wb), you need to multiply the residual permeability of the magnet (Tl \u003d Wb / m2) by the surface area of ​​\u200b\u200bthe rotor ( m2), but this is inaccurate :)
what area of ​​the rotor to take is not very clear a

rotor like this (left)