To design effective vibrotactile actuators or display algorithms, an understanding of the perceived intensity (strength) of their vibrations is essential. This paper aims to build a robust model for the perceived intensities of mobile device vibrations, which can be used by engineers and application designers. We carried out two psychophysical experiments using absolute magnitude estimation procedures. In Exp. I, we investigated the effects of vibration direction and device weight on the perceived intensity of mobile device vibrations. Only the vibration direction was found to be a statistically significant factor, showing the highest perceived intensities along the height direction of a mobile device. In Exp. II, we measured the perceived intensities of vibrations with various amplitudes and frequencies along the three vibration directions. Then, for each direction, a psychophysical magnitude function and equal sensation contours were constructed based on Stevens’ power law. In addition, we found a monotonic relationship between the physical power of vibration absorbed by the hand and the resulting perceived intensity. This suggests that the former, which is greatly easier to acquire in practice, is a reliable predictor of the latter. We expect that the results of this study can provide knowledge about the perceptual strength of vibrations that engineers and applications developers will find useful.