The invention is directed at a method of calibrating a plurality of sensors in a system for obtaining animal data from a group of animals, wherein the sensors are configured to obtain measurements of an animal related parameter, wherein for obtaining the measurements the system is configured for allowing each animal to arbitrary visit one of the sensors, wherein the method comprises: obtaining, for at least one animal of the group of animals, a first measurement associated with a first sensor of the plurality of sensors; calculating one or more relations between the first measurement and one or more second measurements associated with the respective animal, wherein each of the second measurements is obtained using further sensor different from the first sensor, such as to obtain at least one representative relation for each combination of the first sensor and each one of the further sensors; and calculate, based on the at least one representative relation, a correction factor associated with at least one sensor of the plurality of sensors, for harmonizing an output signal of the at least one sensor with respect to output signals of one or more further sensors of the plurality of sensors.