This calculator will give you a rough idea of what your aquarium consumes and costs in power. 
The idea is that your heater is typically only on 1/3 of the time.
Your lights are on 8 hours a day.
Everything else is on 24 hours a day.
Approximate cost of power consumption was taken from the U.S power cost average. 
So while this calculator may not be exact for your area, it will still prove as a good idea as to what your aquarium costs, both daily and monthly.
Enter your total heater watts. (what your heaters rating is)
Enter your total lighting in watts
Add up all other equipment in watts and enter those as well.