How to Calculate your Monthly Electrical Cost.


If your Electrical Bill is running sky high monthly, knowing how they add up might give you a rough idea on where you can save up. In every household, the biggest culprits that can send your Bill sky rocking are:

  1. The Air-Condition
  2. The Refrigerator
  3. The Kettle,
  4. The Rice Cooker
  5. The Hot Plates
  6. The Iron
  7. and whatever that you have in the house that uses some kind of heating elements or motors. (Fans notwithstanding as the motor id so small that consumption is negligible)

How to Calculate the Cost of Running an Air Condition.

To calculate the Amount of money you have to pay to run a 1.5 hp Air-con unit for say, 8 hours, you will need to know the wattage of the unit. Air-cons and all other motors for that matter don’t specify the Wattage on the labels. Instead, they state the Horsepower. So it is suffice to know and memorise that:

1 Hp is equivalent to 746 watts.

The reason we need to know the wattage is simply because our Electrical Meters that we have outside our houses reads in Kilowatt Hours, thus the name kilowatt hour meter. The latest rates charged by TNB is I think, is 0.218 sen for the first 200 Kwh., and 0.258 sen for anything above that (for private homes). You can change that if there is a revision that I don’t know of. So a simple calculation would be:

1.5 hp = 1119 watts
1119 watts x 8 hours/day = 8952 watts
8952 divided by 1000 = 8.952 Kwh
8.952 x 0.218 = Rm. 1.95/day
Rm.1.95/day x 30 = Rm.58.50/month

That’s just a rough idea, but that is roughly how much you will be paying if you run your Air-con for 8 hours a day for 30 days. Bear in mind that the consumption will also go up if the unit is not properly maintained or if it is an old unit that has succumbed to wear and tear.

Using the same formula, you can calculate each and every electrical item that you have in your house, add them together and you can guess roughly how much you will have to pay monthly.

Just for fun’s sake. Lots of people don’t like to light up the dark corners of their houses when they go to sleep at night fearing that they will have to pay extra electrical charges. Just calculate the cost of leaving a 40 watt fluorescent light switched on from 8 pm to 8 am the next morning.

I fluorescent light = 40 watts
40 watts x 12 hrs = 480 watt hour
480 divided by 1000 = 0.48 kwh
0.48 x 0.128 = 0.06 sen per day. (12 hours)
0.06 x 30 = Rm. 1.80 per month.

Is that too much to pay for keeping your compounds lighted up?