The new rating system developed and supported by LG, Motorola, Nokia, Samsung Electronics and Sony Ericsson, ranges from five stars for the most efficient chargers down to zero stars for the ones consuming the most energy.
The measure is a response by the cell phoen industry to heavy criticism from environmentalists. The industry has become the world's top consumer electronics business by volume.
Chargers continue to use electricity if left plugged into the socket, even if the phone is disconnected. Around two-thirds of the electricity used by cell phones are wasted this way.
"If the more than three billion people owning mobile devices today switched to a four- or five-star charger, this could save the same amount of energy each year as produced by two medium sized power plants," Nokia said in a statement.
The world's top four charger makers include Flextronics, China's BYD Co, Emerson Group and Finnish Salcomp.
