They do consume a tiny little bit. I have a Measurement thingy that yoj plug between your outlet and whatever is plugged in which is accurate to 0.1 W. I tryed 3 chargers, one shows 0.1 W, the other two show 0.0 . I still know they consume a tiny bit, but less than 0.1 W is almost nothing. 0.1 W would come out to a consumtion of 0.876 kWh over a year, wich costs me 0.30 €.