The traditional approach to quantifying these things is to buy a Kill-a-watt[1]. Manufacturers don't know about the electricity supply situation (brownouts/sag

The traditional approach to quantifying these things is to buy a Kill-a-watt[1]. Manufacturers don't know about the electricity supply situation (brownouts/sag, line condition, etc.) in your area so the best they could do is ideal numbers. Yours might be 20% worse. Welcome to the rabbit hole of home energy use monitoring! 1. https://en.wikipedia.org/wiki/Kill_A_Watt https://en.wikipedia.org/wiki/Kill_A_Watt