10 watts to kWh per day and month

0.24 kWh/day

for 10 W running 24/7 · 7 kWh/month · $1.19/month at 16.5¢

10 W by hours of use

Use	Per day	Per month	Cost/month
1 h/day	0.01 kWh	0.3 kWh	$0.05
2 h/day	0.02 kWh	0.6 kWh	$0.10
4 h/day	0.04 kWh	1.2 kWh	$0.20
8 h/day	0.08 kWh	2.4 kWh	$0.40
12 h/day	0.12 kWh	3.6 kWh	$0.59
24 h/day	0.24 kWh	7.2 kWh	$1.19

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

0.24 kWh running 24 hours, 0.08 kWh at 8 hours.