Our bill for July was $278.00 and will probably be more for the month of August. We have 2800 sq.ft. and I also have a 400 sq. ft. quilting room separate from the house. I have brought my machine into the house to sew because running the AC out in my room just adds to the bill. We keep ours at 79. We had two new units put in last summer and they just completed putting in all new high energy windows (35) last week. So we'll see if that helps! The heat in Texas this summer is brutel.