I actually plan to make a video soon about how to calculate cost of electricity consumption. But here is the formula:
In order to calculate that you would need to find out the "cost per kWh" from your electricity company. Where I live, the cost per kWh is $0.11 ... Here is the formula:

watts x hours light on per day / 1000 = kWh

kWh x price per kWh = cost per day

Example: 300 x 12 / 1000 = 3.6 kWh

3.6 x 0.11 = $0.40

So it costs $0.40 per day to run 300 watts for 12 hours a day if the cost per kWh is 11 cents.

I actually plan to make a video soon about how to calculate cost of electricity consumption. But here is the formula: In order to calculate that you would need to find out the "cost per kWh" from your electricity company. Where I live, the cost per kWh is $0.11 ... Here is the formula:

watts x hours light on per day / 1000 = kWh

kWh x price per kWh = cost per day

Example: 300 x 12 / 1000 = 3.6 kWh

3.6 x 0.11 = $0.40

So it costs $0.40 per day to run 300 watts for 12 hours a day if the cost per kWh is 11 cents.