Abstract The size effect on the material properties in the micro-forming is examined in the present study using both the micro-hardness test and the finite element analysis. The measured hardness indicates that the hardness decreases as the dimension of the specimen is downscaled to a small size. The size effect on the material hardness is thus clearly observed. The good agreement between the measured hardness and the flow stress also confirms that the theoretical proportionality between the hardness and the flow stress is still valid in a specimen with downscaled dimensions. It suggests that the stress–strain relations of a downsized specimen can be constructed from the micro-hardness tests in conjunction with the compression tests, if the accurate data acquisition is not available in the compression test equipment for a downscaled specimen.