The invention relates to a heat flux comparator comprising two substantially planar and mutually parallel input faces, capable of receiving each a heat flux, and comprising a thermoelectric circuit including at least a strip of a first metallic material partly covered on one of its surfaces with first separate metal pads of a second metallic material. The heat flux comparator also comprises layers of an insulating material arranged on either side of the thermoelectric circuit, second and third pads arranged on respective faces of the two layers of insulating material which are directed away from the thermoelectric circuit. The second and third pads are made of a same material and have substantially a same thickness, and the layers of insulating material have a same thickness too.