1,200 watts to kWh per day and month

28.80 kWh/day

for 1,200 W running 24/7 · 864 kWh/month · $142.56/month at 16.5¢

1,200 W by hours of use

Use	Per day	Per month	Cost/month
1 h/day	1.20 kWh	36.0 kWh	$5.94
2 h/day	2.40 kWh	72.0 kWh	$11.88
4 h/day	4.80 kWh	144.0 kWh	$23.76
8 h/day	9.60 kWh	288.0 kWh	$47.52
12 h/day	14.40 kWh	432.0 kWh	$71.28
24 h/day	28.80 kWh	864.0 kWh	$142.56

kWh = W × hours ÷ 1000. Devices with thermostats or compressors cycle, so actual use is often lower than the rated wattage × hours.

28.80 kWh running 24 hours, 9.60 kWh at 8 hours.