Which makes me notice that 1 kWh / year = 1000 Wh / year = 1000 Wh / (356 * 24h) = 0.117 W. So you can quickly estimate that a device with x Watts of constant consumption will have you paying for roughly 10 x kWh in electricity a year. With electricity costs on the order of 20 cents/kWh, that means a rule of thumb is "double the wattage, that's how many $ it'll cost you to have it running all year".
25 W * 24 h/day * 365 days/year = 219000 Wh/year = 219 kWh/year
Which makes me notice that 1 kWh / year = 1000 Wh / year = 1000 Wh / (356 * 24h) = 0.117 W. So you can quickly estimate that a device with x Watts of constant consumption will have you paying for roughly 10 x kWh in electricity a year. With electricity costs on the order of 20 cents/kWh, that means a rule of thumb is "double the wattage, that's how many $ it'll cost you to have it running all year".