The invention relates to a unidirectional counter comprising a worm wheel (1), which can be driven, and at least one numeric indicator (3), which can be driven by the rotation of the worm wheel (1). Said wheel (1) cooperates with a system wheel (8) by means of a first system of ratchet teeth (6, 7a, b) comprising at least one first pair of equally acting ratchets (7a, b) which cooperate with each other. Moreover, a reversing wheel (10) can be driven by the worm wheel (1), wherein said reversing wheel (10) cooperates with a second system wheel (14) by means of a second system of ratchet teeth (12, 13a, b) comprising at least one second pair of equally acting ratchets (13a, b) which cooperate with each other. The invention aims to count and show the consumed units of energy as precisely as possible, even when there is a change in the direction of rotation. To this end, the transmission ratio between the worm wheel (1) and the reversing wheel (10) and / or between the first and second system wheels (8, 14) is different from 1, which compensates for the slower, system-inherent backwards rotation speed of the rotor disk arrangement in the unidirectional counter.