The method electromagnetically measures a pipe inner diameter ID and a pipe ratio of magnetic permeability to electrical conductivity .mu..sub.2/.sigma..sub.2 by means of a measuring arrangement 1 comprising a transmitter coil 2 and a receiver coil 3, both coils being coaxial to and longitudinally spaced from each other, the measuring arrangement 1 being adapted to be positioned into the pipe CS and displaced through the pipe. The method comprises the steps of: a1) exciting the transmitter coil 2 by means of a transmitter current I.sub.i, the transmitter current having a first excitation frequency f.sub.1, a2) measuring a receiver voltage V.sub.i at the receiver coil 3, a3) determining a transimpedance V.sub.i/I.sub.i between the transmitter coil 2 and the receiver coil 3 based on the transmitter current I.sub.i and the receiver voltage V.sub.i, and determining a measurement ratio M.sub.i based on said transimpedance, b) repeating the excitation step a1), the measuring step a2), the transimpedance and the measurement ratio determination step a3) for at least a second excitation frequency f.sub.2 so as to define a measurement ratio vector [M.sub.1, M.sub.2, . . . M.sub.n], c) calculating a prediction function vector [G.sub.1, G.sub.2, . . . G.sub.n] based on the first and at least the second excitation frequency, a plurality of potential pipe ratio of magnetic permeability to electrical conductivity and a plurality of potential pipe inner diameter ID, and d) applying a minimizing algorithm onto the measurement ratio vector [M.sub.1, M.sub.2, . . . M.sub.n] and the prediction function vector [G.sub.1, G.sub.2, . . . G.sub.n] and determining the pipe inner diameter and the pipe ratio of magnetic permeability to electrical conductivity corresponding to a maximum solution of the algorithm.