There is provided a method of estimating a position of a handheld personal care device relative to a user of the handheld personal care device, the method comprising obtaining one or both of (i) measurements of a weight distribution of the user in a predetermined area over time and (ii) measurements of a torque imparted to the predetermined area by one or both feet of the user over time; and estimating the position of the handheld personal care device relative to the user using the obtained measurements and based on a predetermined relationship between the weight distribution and/or the torque imparted and the position of the handheld personal care device relative to the user.