A wearable device comprising a heart rate determining component for determining the heart rate of a wearer of the wearable device and a heart rate sensing module fixed on the wearable device, the wearable device intended to be worn by a user, the module comprising: at least one contactless sensor adapted to sense at least one parameter indicative of the distance between at least a reference point of the skin of the user and a reference point of the module when the wearable device is worn by the user in such a manner that the contactless sensor is distant from the skin of the user, at least one communication entity adapted to communicate data indicative of the at least one parameter sensed by the at least one contactless sensor to the heart rate determining component, the heart rate determining component comprising: a communication unit configured to receive data indicative of the at least one parameter sensed by the at least one contactless sensor of the heart rate sensing module, and a heart rate unit comprising at least a memory configured to store computer executable instructions; and a processor for executing the computer executable instructions, wherein the computer executable instructions comprises instructions for determining heart rate data indicative of the heart rate of the user based on the received data, characterised in that the wearable device further comprises one of a time of flight sensor configured to sense the distance between the wearable device and the user of the wearable device and an infrared reflectance based proximity sensor to sense the proximity between the wearable device and the user of the wearable device, and in that the wearable device further comprises an accelerometer and/or a gyroscope configured to sense the orientation of the wearable device. at least one contactless sensor adapted to sense at least one parameter indicative of the distance between at least a reference point of the skin of the user and a reference point of the module when the wearable device is worn by the user in such a manner that the contactless sensor is distant from the skin of the user, at least one communication entity adapted to communicate data indicative of the at least one parameter sensed by the at least one contactless sensor to the heart rate determining component, the heart rate determining component comprising: a communication unit configured to receive data indicative of the at least one parameter sensed by the at least one contactless sensor of the heart rate sensing module, and a heart rate unit comprising at least a memory configured to store computer executable instructions; and a processor for executing the computer executable instructions, wherein the computer executable instructions comprises instructions for determining heart rate data indicative of the heart rate of the user based on the received data, characterised in that the wearable device further comprises one of a time of flight sensor configured to sense the distance between the wearable device and the user of the wearable device and an infrared reflectance based proximity sensor to sense the proximity between the wearable device and the user of the wearable device, and in that the wearable device further comprises an accelerometer and/or a gyroscope configured to sense the orientation of the wearable device. a communication unit configured to receive data indicative of the at least one parameter sensed by the at least one contactless sensor of the heart rate sensing module, and a heart rate unit comprising at least a memory configured to store computer executable instructions; and a processor for executing the computer executable instructions, wherein the computer executable instructions comprises instructions for determining heart rate data indicative of the heart rate of the user based on the received data, characterised in that the wearable device further comprises one of a time of flight sensor configured to sense the distance between the wearable device and the user of the wearable device and an infrared reflectance based proximity sensor to sense the proximity between the wearable device and the user of the wearable device, and in that the wearable device further comprises an accelerometer and/or a gyroscope configured to sense the orientation of the wearable device.