In a method for determining an acceleration factor of a parallel image acquisition for a data acquisition direction of a measurement volume by means of a magnetic resonance device having multiple coil units, each coil unit emits at least one output signal for parallel image acquisition and wherein an acceleration contribution is assigned for at least one direction (X,Y,Z) for a sensitive volume. Relevant coil units, which by virtue of the arrangement of their sensitive volume in relation to the measurement volume contribute to the acceleration, are specified. The data acquisition direction in the measurement volume is specified and the acceleration factor in this direction is determined by means of acceleration contributions depending on the position of the relevant coil units with respect to one another and the position of the relevant coil units in relation to the measurement volume and to the data acquisition direction.