Method for calculating the activity of a user, said method being implemented by a portable electronic first device consisting of a personal activity monitor intended to be securely associated with the body of the user and capable of detecting the accelerations experienced, and by a portable electronic second device consisting of a smartphone equipped with a geolocation function, the first and second devices being physically independent and configured to exchange data over a wireless connection, the first device having in a memory different average step values (MKO-U) according to the different types of activity, for the user to which the first device is associated, and the method comprising the steps of: -a - the first device measuring the signals of accelerations experienced and counting substantially continuously the steps or cycles performed by the user, -b - the second device determining the current geolocation of the user at a first time, which constitutes the first geolocation, -c - the second device determining the current geolocation of the user at a second time, which constitutes the second geolocation, -d - one of the two devices (1,2) calculating a first distance traveled, D12 between the first and second geolocations (A1,A2), -e1 - deducing, based on the levels of acceleration experienced between the first and second times (T1,T2) and on the first distance traveled, D12, the current type of activity among a plurality of types of activity including walking, running, bicycling, horseback riding, racket sports, and golf, -e2 - deducing a calculation of the calorie expenditure between the first and second times, -e3 - if the current type of activity is walking, running, or bicycling, the first device calculating, by means of said first distance traveled, D12, and the number of steps taken between the first and second geolocations (A1,A2), the average stride and/or average step and/or average gear ratio of the user between the first and second geolocations, such that the first device is updating an average step value (MKO-Ui) according to the corresponding type of activity, thereby personalizing its own data concerning that particular user. -a - the first device measuring the signals of accelerations experienced and counting substantially continuously the steps or cycles performed by the user, -b - the second device determining the current geolocation of the user at a first time, which constitutes the first geolocation, -c - the second device determining the current geolocation of the user at a second time, which constitutes the second geolocation, -d - one of the two devices (1,2) calculating a first distance traveled, D12 between the first and second geolocations (A1,A2), -e1 - deducing, based on the levels of acceleration experienced between the first and second times (T1,T2) and on the first distance traveled, D12, the current type of activity among a plurality of types of activity including walking, running, bicycling, horseback riding, racket sports, and golf, -e2 - deducing a calculation of the calorie expenditure between the first and second times, -e3 - if the current type of activity is walking, running, or bicycling, the first device calculating, by means of said first distance traveled, D12, and the number of steps taken between the first and second geolocations (A1,A2), the average stride and/or average step and/or average gear ratio of the user between the first and second geolocations, such that the first device is updating an average step value (MKO-Ui) according to the corresponding type of activity, thereby personalizing its own data concerning that particular user.