We are in the process of an experiment. I'm not sure how exact it will be but...
I read our meter at arrival here in the valley and have used LP for everything. Heat, HWH and fridge. We used the A/C for maybe 2-1/2 days maybe 10 hours total. Our usage was 110 KWH for 14 days. At that 14 day mark, I switched everything over to electric. We are still using the furnace but it doesn't run too often. During the first two weeks I filled 2- 30# LP bottles. Not sure how empty the first one was but from the time I switched to a full bottle a week passed before the 2nd ran out. So it looks like I'm using 1 bottle per week.
At the end of the next 2 weeks I'll read the meter to check the difference.
Propane here is $17.75 for a 30# bottle and electric is .19/hour, eek!