In general, the higher the BTU rating, the more electricity your unit will pull. And, of course, the energy draw will vary by make and model. 6,000 BTU Air Conditioner (approximately 560 watts). This unit could cool a room up to 260 sq. ft. 1  24 hours/day: $2.42 per day or $72.58 per month.2  The math: (560/1,000) x ($0.18 per kWh) x 24 hours per day x 30 days. 3  12 hours/day: $1.21 per day or $36.29 per month.,000 BTU Air Conditioner (approximately 560 watts). This unit could cool a room up to 260 sq. ft. 1  24 hours/day: $2.42 per day or $72.58 per month. 2  The math: (560/1,000) x ($0.18 per kWh) x 24 hours per day x 30 days.