Electricity usage is the amount of energy your household consumes, measured in kilowatt-hours (kWh). Appliances with higher wattage, or those used for longer, generally use more electricity—for example, running a heater for several hours can add more usage than charging a phone. Your bill may also include daily supply charges, and your retailer’s rates, tariff structure and billing period affect the total cost. Check your bill or smart-meter data for usage patterns, and contact your retailer if the readings seem unusual.