Design, fabrication and test of cantilever-type sensors for active micro force calibration are described. The cantilever comprises a probing tip at its free end where a force can be applied which is measured using a piezoresistive strain gauge at the cantilever suspension. The stiffness of the cantilever is approximately given by the spring constant of a beam with a rectangular cross section as confirmed by finite element modelling. Prototypes with a stiffness of 0.66 N m−1 and 7.7 N m−1 are realized using standard silicon bulk micromachining technology. Testing is performed using a high-resolution micro force measuring set-up. In either case a highly linear relationship between the gauge output voltage and the probing force is revealed in the µN range. Low scatter and drift corresponding to a standard deviation of ±0.22% was found for the resulting force sensitivity.