# How electricity bill is calculated, What makes electricity bill high

Electricity bills are calculated from the reading taken monthly on your electric meter. The best way to understand what electricity is, is to think of electricity as water under pressure which can turn your fan and make the lights come on. So the electricity meter is like a water meter measuring how much quantity has been consumed. Like the measure of water is a ‘Liter’, the measure for electricity is called a ‘Kilowatt-Hour’ commonly referred to as a ‘Unit’ of Electricity.

To give an example of how electricity is measured, imagine a ceiling fan of 100 watts working for 10 hours. The electricity consumed by this fan will be the fan watts multiplied by the time it runs. So  100 watts x 10 hours = 1000 watt hours. 1000 watts is 1 Kilowatt, so 1000 watt hours will be equal to 1 Kilowatt hours or 1 unit of electricity. If this fan works for 10 hours daily for 30 days or a month, then the monthly electric bill for the fan will be 30 days x 1 unit per day = 30 units in a month. Assuming a unit of electricity costs Rs.5-, then the monthly electricity bill for this fan will be 30 x 5 = Rs.150- per month.

## How to reduce electricity usage

What makes house electricity bills high are the use of high power consuming electric appliances and the use for long time of fans, lights, etc. So these are some of the ways to save and reduce electricity use at home and thereby reduce house electricity bill:

1. Use less watt electrical bulbs, like LED bulbs which give same light output but using less watts.
2. Reduce the time of operating electrical equipment like fans.
3. Use star rated electrical appliances like fridge, ACs, etc.
4. Electrical heating uses lots of current or electricity. So do not use electricity for cooking.  Normal Electric water heaters in the bathroom consume around 2 to 2.5 units of electricity per hour. Use of a solar water heater can save quite a bit of money.
5. Talking of solar, if you have the possibility of having a grid connected solar power system installed in your house, then it could be possible to get your electricity free with no monthly electric bill at all. I have
in my house a 4 KW solar power system with 16 solar panels connected to the Government Electricity Board Grid. Even though I am using an AC daily in the night, I get no electricity bill, it is free. So a Solar Grid connected System is the best solution for high electricity bills.

Let us work out a real world example of trying to calculate the expected monthly electricity bill for a typical middle class family in India. The following table gives the wattage and daily usage time of typical household appliances owned by a middle class family in India. The total electric power consumption is calculated as follows:

Monthly electricity bill calculation
ApplianceWattsNo.HoursWatt x HoursUnits /day
CFL Bulbs15844800.48
Cieling Fans1003824002.40
TV 32 inch LED40141600.16
Fridge 250L 4★ 501 U/year*241.37
Micro wave70010.53500.35
induction cooker12001112001.20
Air Fryer150010.55000.5
Others150134500.45
Total7.01

To calculate the monthly electricity bill, the total daily usage of 7 Kilo-watt hours calculated in the above table has to be multiplied by 30. So 7×30=210 Kilowatt hours or 210 units of electricity a month. If the charge for electricity is ₹5- per unit then the monthly electricity bill would be Rs.1050-

How some of the items in the above table is worked out is explained like this. For the example of ceiling fans of 100 watts each. We assume daily usage of 3 fans running for 8 hours daily. So you consume 100 watts x 8 hours x 3 fans = 2400 watt-hours which is = 2.4 Kilo-watt hours, since 1000 watts makes 1 Kilowatt. So every day you consume 2.4 Units of electricity when you use the 3 fans of 100 watts each for 8 hours a day.

Similarly for 8 CFL bulbs of 15 watts each used for 4 hours daily on an average, the total current consumption of the CFL lamps will be 8x15x4=480watts and for a month the current consumption of the 8 CFL lamps will be 480/1000=0.48 KWH or units of electricity in a month.

For the fridge we have taken the annual consumption of a 4★ (4 star) rated fridge of 250 Liter capacity as 501 units in a year running 24 hours daily for 365 days in a year. This information is obtained from the Government of India’s Bureau of Energy Efficiency. Dividing 501 by 365 gives us the daily power consumption of the fridge as 1.37 units a day.

In the case of an Air fryer 1500 watts is the highest power on Air fryer models. The maximum time an air fryer needs to cook a main meal is about 30 minutes. During this 30 minutes, the air fryer heater will not be ‘ON’ all the time, meaning that there will be intervals when the heater coil will be switched off by the automatic temperature control when the cooking temperature has reached the set cooking temperature. The heater of an air fryer consumes more than 90% of the power, the blower and other parts together consume less than 10% of the power. So it can be safely assumed that the air fryer heater coil power is ‘ON’ for two thirds of the time during cooking and one third of the time the power to heating coil will be ‘OFF’.

Two thirds is = 0.67 and 30 minutes = 0.5 hours. So the air fryer will consume 1500×0.5×0.67 = 502.5 watt hours or approximately 0.5 Kilo-Watt Hours or half a unit of electricity per air fryer cooking cycle of 30 minutes.

An air fryer cooking time with 30 minutes is only reached on rare occasions, most of the recipes for air frying takes only about 15 minutes on an average. Thus the maximum electricity an air fryer can use is not more than half a unit of electricity in a day. In case you do 2 air frying cooking of 30 minutes each, the maximum electric power consumed by the air fryer will only be 1 unit of electricity in a day. The Air Fryer in the example given above is the one with 1500 watts power, but most of the Air Fryers have a power rating which is less than 1500 watts and therefore consume much less than the half unit of electricity in a day.

## Electric power used by domestic appliances

We have provided below a table with the approximate wattage of some typical everyday used electrical appliances. Most of the electrical domestic appliances have their wattage on a label prominently fixed or stamped on the appliance. So that way you will know exactly how many watts the appliance consumes.

TYPE OF APPLIANCEWATTS
TUBE LIGHT (Electronic Choke)36
TUBE LIGHT (Ordinary Choke)52
CFL BULB15
CEILING FAN / TABLE FAN40
CEILING FAN BIG75
PEDESTAL FAN100
EXHAUST FAN100
KITCHEN CHIMNEY350
FRIDGE 165 LTRS100
FRIDGE 310 LTRS400
MICROWAVE OVEN 1000
LED TV 40 INCH100
DESKTOP COMPUTER100
LAPTOP CHARGER25
PRINTER25
WATER PUMP 0.5 HP375
TYPE OF APPLIANCEWATTS
ELECTRIC IRON750
INDUCTION COOKER1200
TOASTER750
MIXER GRINDER (BIG)400
MIXIE (SMALL)250
GEYSER 12000
WATER HEATER1000
ELECTRIC KETTLE1500
ELECTRIC OVEN 1750
DISHWASHER1200
VACUUM CLEANER500
ROOM A/C 1 TON1400
ROOM A/C 1.5 TON2100
AIR COOLER250