A fiber optic modem typically consumes between 5 to 15 watts per hour, translating to roughly 0. This means How Many Watts Does A Fiber Optic Modem Use A Day? is a surprisingly small number compared to other household appliances. The power consumption of a device can be calculated using the following formula: Power consumption (kWh) = Power (kWh) x Time (hours). 005 kWh per hour (5 watts/1000). You may also want to know: Are Bing and Yahoo. The broadband router electricity cost is the amount of money spent on electricity to keep your home router running — typically 24 hours a day, 7 days a week. Average Wi-Fi routers use about 7. 168 kilowatt-hours per day, which is quite minimal in the context of overall.