500 watts to kWh per day and month

12.00 kWh/day

for 500 W running 24/7 · 360 kWh/month · $59.40/month at 16.5¢

500 W by hours of use

Use	Per day	Per month	Cost/month
1 h/day	0.50 kWh	15.0 kWh	$2.48
2 h/day	1.00 kWh	30.0 kWh	$4.95
4 h/day	2.00 kWh	60.0 kWh	$9.90
8 h/day	4.00 kWh	120.0 kWh	$19.80
12 h/day	6.00 kWh	180.0 kWh	$29.70
24 h/day	12.00 kWh	360.0 kWh	$59.40

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

12.00 kWh running 24 hours, 4.00 kWh at 8 hours.