I see this question from time to time and always through it was fairly accurate but never quantified it. Today I looked at my last five utility bills and what Sense claims was used over the same period. Over the entire five month period the utility says I used 7946 KWH while Sense shows that I used 7934 KWH. That is a difference of only 12 KWH for the entire five month period. I don’t think even another revenue meter would match much closer than that.