Steam irons generally consume around 1 kW of power while in use and this varies with different steam iron models. Generally, the more powerful your steam iron is, the more electricity it will consume while in use. Also, know that some advanced steam irons have energy saver settings that reduce power consumption when not in use. Steam irons are generally less expensive to run than other electrical appliances like hair dryers or ovens since they only need 1 kW of power to operate.