The effect of uniaxial mechanical stress on the magnetic properties of electroplated Nifilms was measured with a magneto‐optical Kerr loop tracer. We show that the effect of stress on the coercive force is completely different for thin (20 nm) and thick (10 μm) films. The latter behaves like bulk Ni, whereas results on lower thicknesses show a continuous transition from thin film to bulklike behavior. The results are discussed by assuming different micromagnetic reversal processes for the two extremes: rotational for thin film and domain wall movement for bulk.