How to calculate monthly electricity bill?

In Malaysia, Tenaga Nasional Berhad (TNB) domestic rate is (based on 1st Mar 2009):

For Monthly Consumption Between 0-400 kWh/month
For the first 200 kWh (1 - 200 kWh) per month: 0.218 cents
For the next 200 kWh (201 -400 kWh) per month: 0.334 cents
* The minimum monthly charge is RM3.00

For Monthly Consumption More Than 400 kWh/month
For the first 500kWh (1-500kWh) per month: 0.286 cents
For the next 100 kWh (501-600kWh) per month: 0.378 cents
For the next 100 kWh (601-700kWh) per month: 0.387 cents
For the next 100 kWh (701-800kWh) per month: 0.397 cents
For the next 100 kWh (801-900kWh) per month: 0.417 cents
For the next kWh (901 kWh onwards) per month: 0.446 cents
* The minimum monthly charge is RM3.00
TNB Dosmestic Rate

Every electrical appliances should have Watt (W). This is the info that you need to calculate your monthly bill. However, some product doesn’t display Watt, but only Volt (V) and Ampere (A). To get Watt, just multiply volt and ampere. Meaning, V x A = W.

Formula to calculate electricity usage.
Watt x Hours / 1000 = kWh

Now you’ve got all the information that you need to calculate, let’s try calculating something.
If you use a Philips 18W bulb for 8 hours a day a month. How much is the charges?
18W x 8 Hours / 1000 = 0.144 kWh
0.144kWh x 0.218 = RM0.031392 per day
RM0.031392 x 30 days = RM0.94176

Philips 18W bulb is Energy Saver bulb. You pay less than a dollar for 8 hours a day usage.

Let’s try another calculation.
Panasonic 1 hp (2.7kW) air con.

How much is the charges for the whole month?
2.7kW x 8 hour = 21.6 kWh
21.6kWh x 0.218 = RM4.7088
RM4.7088 x 30 days = RM141.264
If you switch on aircon everyday for 8 hours, your aircon usage will be RM141 per month. Most of the time, it is really hot & you need to switch on aircon to have a sweet dream.

Hope above information will help you to plan your monthly electric usage & choose energy saving electrical appliances.
Save energy = save money

TNB will review electricity rate again next month. Let's see what surprised we are going to get.