So, To convert these wattages into a daily use of kilowatt hours (kWh – the standard billing unit of electricity suppliers), the following equation applies -. (Wattage x eight) ÷ 1000 = kWh per day. Where eight represents our presumed eight hours active time per day. Thus a 600 Watt unit – typical of older, larger refrigerators – would use 4.8 kilowatt hours daily, or 1750 per year; where a more modern 140 watt unit uses about 1.1 kWh daily, or approximately 400 per year. This is how many watts does a refrigerator use. No information is provided by the author.