Electricity Saving Tips For Homes And Offices

What are Watt, Kilowatt and a unit of electricity

By on April 22, 2016

When we get our electricity bills, it shows that we have used a certain number of units for the given period. When we go to buy appliances, most of them have watts mentioned on them. If you find it difficult to understand the relation between the two, then you are not alone. Electricity bill and its components are confusing to many and with this article we will try to explain what are watt, kilowatt and a unit of electricity.

Power and Energy/Electricity

Power and Energy/Electricity are two words that are used so much for each other that many feel that they mean the same. Interestingly both of them have a very different meaning. Power is the rate at which electricity is used and energy/electricity is the actual consumption. To give an analogy, power is similar to speed but electricity/energy is the actual distance travelled.

So        Power x Time = Electricity (or energy)

Just like          Speed x Time = Distance Travelled.

Power and its units

Power is always represented in watt (W) or kilowatt (kW). A thousand (1000) watts make one kilowatt. So if any appliance is rated as 1.2 kW then it means that it consumes electricity at a rate of 1200 W. Now as we discussed earlier that power is the rate at which electricity is consumed and not the actual electricity consumed, Watt or Kilowatt just represent the rate at which electricity is consumed per hour. Which means that when you buy a 100 W bulb, it does not consume 100 units of electricity but consumes at a rate of 100 W.

Energy/Electricity and its units

A unit (as mentioned on the electricity bills) is represented in kWH or Kilowatt Hour. This is the actual electricity or energy used. If you use 1000 Watts or 1 Kilowatt of power for 1 hour then you consume 1 unit or 1 Kilowatt-Hour (kWH) of electricity. So the reading on the electricity meter represents the actual electricity used. Just like the odometer on your vehicle that shows the actual distance travelled by the vehicle, electricity meter shows the amount of electricity that is used. So a 100-Watt bulb if kept on for 10 hours will consume:

100 x 10 = 1000 Watt-Hour = 1 Kilowatt-Hour (kWH) = 1 units (on your meter).

Estimating units consumed by any appliance

Now with most of the concepts explained we would like to make it easy for you to calculate how much units does any appliance consume. Most appliances have wattage written on them (either on their container box or somewhere on the appliance). Once you have the wattage, next you need to figure out how many hours a day do you use it. After that you can use the formula below:

Daily Units = (Wattage x Usage hours per day) ÷ 1000

Monthly Units = Units x 30 (or 28,29,31 based on month)

Please note that this formula may not work always. For appliances like Air Conditioner, Water Heater, Cloth Iron (any heating or cooling device) and pumps, this will not work.

Infographic3

Check this video to make it easier to understand:

Also check this video that can help you understand how many units your appliances are consuming:

Source of Information:

http://www.energysavers.gov/your_home/appliances/index.cfm/mytopic=10040

http://en.wikipedia.org/wiki/Watt#Confusion_of_watts.2C_watt-hours.2C_and_watts_per_hour

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102 comments

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1

Hi Abhishek i bought a Air conditioner ( Voltas 185 LY ) which has power consumption of 1495 watts . Could you please tell me how much power does it consumes if i turn it on for 6 hours on daily basis.

2
Abhishek Jain (Mod)

Difficult to tell exact value but to get an approx, it would be 1495*0.7/1000 = about 1 unit in an hour. So 6 units per day.

3

Hi Abishek i bought a Air conditioner(ASGA18FMTA) which has power consumption of 1830 watts . Could you please tell me how much power does it consumes if i turn it on for 4-6 hours on daily basis. I will maintain in it A/C in 24 degrees at max.

4
Abhishek Jain (Mod)

Difficult to tell the exact amount as it depends on the heat load. But at a very high level assuming it is right sized, it will have cycle time of 75% (running for 45 mins in an hour), then the power consumption would be 1830*0.75 = 1372.5 Wh or 1.3725 units in an hour. In 6 hours it would consume 8.235 units. And this is assuming you have rightsized the AC and it is run at 25 degrees. At 24 degrees it may go up to 9 units.

5

thanks for prompt reply :)

6

Hi Sir,
I want to shift on Solar enrgy. i live in apartment but having sun light 7-8 hour directly on my window. no obtecals.
My electric bill is an average 150 unit and in summer 220 unit.
can u guide me for my requirment.
as per my understanding
2 -3 solar panel
not sure what type & capacity of battery need ..?
please suggest.

Regards,
Mahesh Lad

7
Abhishek Jain (Mod)

Hello Mr Lad,

Solar Panels have to be in right inclination and direction to get the right output. I am not sure where you live, but in Mumbai it should be inclined at 18 degrees and should face south. On a window it will be at 90 degrees. So I doubt that it will work for you in an apartment.

8

Hello

I live in Goa. I do not switch off our room light (tube light) and leave it on everyday (4 to 5 hours usage everyday) is it such a big deal? i do this because the tube light starter might get worn out sooner than later. But Im not sure if I am doing the right thing, trying to save money on a starter or paying more on electricity? your assistance would be appreciated.

9
Abhishek Jain (Mod)

It is better to switch off the light when not in use. The starter will not get worn out because of that. Also these days most tubelights have electronic ballast that are really long lasting. Do you have old tubelights with starter and electromagnetic ballast?

10

Abhishek Jain - GOD BLESS YOU (Thank you for sharing your knowledge)

11
Abhishek Jain (Mod)

Thanks Santosh. We are glad that you found the website useful. Thanks a lot for the appreciation.

12

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13

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14

Hello, I have 3 Ac at my Home I just wants to know which Ac is Consuming How much Electricity.
O General 1.5 Ton 5 Star Split Ac for 6 Hours. (Room Size 9 x 12 Ft Master Bedroom)
Panasonic 1.5 Ton 2 Star Split Ac for 6 Hours. (Room Size 9 x 18 Ft Hall)
Voltas 0.75 2 Star Window Ac for 6 Hours. (Room Size 7 x 6.5 Ft Small Bedroom)

Your Reply will help me a lot Thank in Advance.

15
Abhishek Jain (Mod)

Hi Naveed,

There are two ways you can do it. The cheaper option is to buy a submeter from the market and get it fabricated by a local electrician in the manner explained in this post: http://www.bijlibachao.com/assessment/measuring-electricity-consumption-of-home-appliances-and-doing-self-audit.html

The other slightly expensive ways is to go for a kill a watt meter that can handle 15 Amp current. More on kill a watt meter on this post: http://www.bijlibachao.com/electricity-bill/kill-a-watt-meter-p3-power-analyzer-powermeter.html

You can get kill-a-watt meter on any ecommerce site (Amazon or ebay). But just make sure that it can handle 15 Amp current (so that it can handle your ACs).

16

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17

I want a solar water heater for my hostel purpose what will be the cost

18

Sir, 25 Hp Power use 10 hours in a day so how many units readings

19
Abhishek Jain (Mod)

1 Hp is 750 watts. You can use the formula given above on this page to do the calculations.

20

Hello abhishek sir please tell me that when i use a 15W tubelight and a ceiling fan for 20 hours and one 10 W tubelight for 6 hours then how much unit consumed by me in a day. Please sir reply fast

21
Abhishek Jain (Mod)

The formula for calculation is given above on this page. Please use the same.

22

I run a Desktop Computer (with CRT monitor) for 16 hours everyday,
Two 40watt Lights 5pm to 1am,
One mini speaker 2.1,
One table fan(it has 3 gears speed system) for 12 Hours everyday,
One Ceiling Fan almost 18 Hours everyday,
One Samsung TV 21 inch (it has 4* energy saving sticker) runs for 7 Hours everyday.
Three Mobiles of 2700mah battery charges 2 times everyday.

in the end I get 170 units Electric bill....
Is it normal or the bill is very high/low according to the usage?

23
Abhishek Jain (Mod)

170 units sounds normal for your usage. Your two fans (ceiling fan, table fan) and your computer would consume most of the electricity.

24

Please tell me if same formula will be applicable on commercial pizza oven. It say 2kw.

25
ROOPCHAND CHHONKAR

How many units are use in a months by 1kwh connection please clear

26
Abhishek Jain (Mod)

1 kWh is 1 unit of electricity.

27

Time is ,Hours, second,

28

sir i use in my house . 2 cooler . 3 roof fan . i hp water moter . 3 led bluf 10 watt ( 3 to 4 hours) 2 cfl 25 watt.
than i gat received ele bill 2 month 27000 rs of 4000 unit .
pls given right information for this mate.

thanks

29

Sir in room I use 1tube light ND one fan how many unite im using in one day then rply fst

30
Abhishek Jain (Mod)

It depends on how many hours you use them for. If you do not switch them on then you use 0 units. But if you keep them on for 24 hours, then you use a lot of units.

31

I am thinking for Solar Power for my House, so could you please guide me tht how much power consume a day based on electronic devices like Fridge, TV, lights, FAN, Washing Machine, Cooler, Water pump, laptop, computer etc....

my house is 3 BHK house.

so my question is how many solar panel I'll require for the same.

32

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33
Abhishek Jain (Mod)

Would suggest you to look at this video: This can answer a lot of your questions.

34

what is the relationship between voltage and wattage,will be happy for the answer.

35
Abhishek Jain (Mod)

If power factor is 1, Wattage = Voltage x Current otherwise Wattage = Power Factor x Voltage x Current.

36

Also sir, tell me if all the using things are work properly then how many units will came as per my last question.

37
Abhishek Jain (Mod)

Your 21 inch TV for 8 hours would not use more than 1 unit.

Cooler for 2 hours would consume about 0.7-0.8 units.

Fridge depending on size should not consume more than 3 units per day (I am not sure about the size and type of your fridge, but any model which is about 500+ litres and double door consumes about that much). And I am sure your fridge would be small, but still assuming on higher side, it should not consume more than 3 units.

38

fridge model : kelvinator 175ltrs

39
Abhishek Jain (Mod)

175 lts fridge should not consume more than 2 units of electricity in a day.

40

Abhishek Sir,I already do this last night but unit still remain. Suggest me is there a fault in meter or there are some additional wire attached with our sub- meter.

41

Hi Sir, My name Is Ravi Thakur, i live in punjab on ranted room. i have a samsung TV 21inches, a fridge, a cooler. In a single day we used tv for approximatly 8hours, cooler for hardly 2 hours & fridge for near about 18 hours in a day. But our unit came 7-8 unit. we think unit are very high. Please suggest us can 7 or 8 unit are rights as per our uses. Also there are electricity cut 2 or 3 hours in a day

42
Abhishek Jain (Mod)

7-8 units sounds high but do check your fridge. Sometimes fridges consume a lot of electricity if they are not efficient or are not being used properly. Try switching it off one day and then measure daily consumption.

44
Abhishek Jain (Mod)

Hi Anil,

It depends on the precision and quality of energy meter. If you get a good meter, you can calculate power of each and every machine running your plant accurately. You can also measure other vital factors like power factor , kVA, kW, kVAH, kWH using a good digital energy meter.

45

Sorry with out energy meter how can we find our power consumption

46
Abhishek Jain (Mod)

You just put it between the machine and the power supply. It should get the value for you. If it is a big machine, go for a 3 phase energy meter with CTs.

47

Sir how much units does an automatic washing machine of 438 kwh will consume with a family of 4 and we have 2 Ac and use it each for 6 hours a day with both 3 star and 1.5 tons ??
Please reply..

48
Abhishek Jain (Mod)

It is 438 Watts or 438 kWh? Because 1 kWh = 1 unit. And 100 Watts when run for 10 hours consumes 100x10 = 1000 Wh or 1 kWh or 1 unit of electricity.

49
Naturaal Engineering Solution

Sir, if 2 kw is consumed in 30 minutes. How much unit consumed?

50
Abhishek Jain (Mod)

2 kW x 0.5 hr = 1 kWh = 1 unit.

51

Hello Abhishek sir,how to check load in three phase electrical panel on multimeter or clamp meter ?

52
Abhishek Jain (Mod)

You need a 3 phase energy meter with CTs (current transformers).

53

How much unit does 8 watts wireless router consumes considering it is on whole month?

54
Abhishek Jain (Mod)

If you use it for 24 hours then in 24 hours it would consume 8 x 24 = 192 Wh or 0.192 kWh or 0.192 units. If you use it for 30 days, you can multiply that by 30 and get the number.

55
Raghavendra Goggi

in our utility panel meter is showing 14871.1 kwh ( one month differnec) ct ratio is 200/5 how to convert this into units

56
Narendra Pandey

how much unit of electricity a geyser of 3000 kwh will consume consume using on an average 45 minutes a in day..?

57
Abhishek Jain (Mod)

Depend on the volume of hot water you use. It does not depend much on the Wattage of the geyser. Check out this post on our website that explains in detail: http://www.bijlibachao.com/water-heaters/choose-the-right-sized-water-heater-geyser-for-electricity-saving.html

58

how much unit consume a normal cooler

59
Abhishek Jain (Mod)

About 250-300 watts which means in an hour about 0.25 to 0.3 units.

60

iDear Sir,
Capacity of 1.5 Sq mm wires is 15 Amps Max. hence power can utilized more compared to 1 sq mm connecting same load, If i connected same load by using 1 sq mm. power consumes in individual connected energy will less. can I presume that lower the current capacity of wire, higher in savings, electricity.
if not please request to explain, why the users are playing, non standard wires with standard wires. no matter in individual connections Watts of 1 KW lamps will less because of poor amp capacity compared to standard.
If I made same connection with single bench circuit, with single source load, week wire consumes more power compared to standard, even after current flow is lesser than standard wire.
I have made experiment connecting 1 KW- 2 Halogen light in parallel with energy meters,in single circuit, current shows in wire 5.85 Amp,in one and and 2.84 in 2 nd, because of connections in parallel circuit 230 V remains same, and also light intensity, but energy shows more in 2nd week wire connected bench circuits.
As current flows in week wire is 2.84^2 X Resistance losses is low in poor quality wires.

61

I observed the reading on the meter on the day the electricity dept took the reading. It was at 31640 kwh... the next day night (roughly 36 hours), the meter read 31655 kwh, a whopping 15 units!! We don't have an air conditioner, no geysers. We did not run the washing machine that day. Just 3 fans with usage not more than 10 hours a day, 3 tube lights with less than 10 hours usage, a crt tv with 10 hours usage and a refrigerator running all day. I just used the induction cooker to heat water for around 15 minutes in the morning. How could all this sum up to 15 units for 36 hours? Am i missing something or should I get the meter checked?

62
Abhishek Jain (Mod)

Hi Vignesh,

Assuming your fans consume 100 watts (worst case), then in 10 hrs each fan would consume 1 unit. So 3 units per day for the fans (max 6 units assuming 2 days). Each tubelight would consume 50 watts (again worst case), then in 10 hrs each tubelight would consume 0.5 units, so 3 tubelights in 2 days would consume 3 units. CRT TV would consume 150 watts, so in 10 hrs it would consume 1.5 units. Again assuming 2 days it would be 3 units. Power consumption of refrigerator would depend on size, technology, etc. But assuming 2 units in a day, in 2 days it would consume 4 units. Induction cooker in 15 mins would consume 0.5 units in worst case. So it totals up to 6 (fan) + 3 (lights) + 3 (TV) + 4 (Refrigerator) + 0.5 (induction) = 16.5 (approx) for 48 hours. This can have some errors as there are approximation and these are not real measurements. Your refrigerator may be a bit more inefficient (or may be big as I have assumed 250 lts old one).

63

Dear Sir,
I M using Ele cooktop 2000watt 2hour in kitchen and water Heater 2000watt 30 min. Please Tell me My Daily elec Unit Usage

64
Deepakkumar Singh

4 Unit For Cooktop + 1 unit For Heater = 5 Unit

65

Sir, my room size is 15x15 feet, i have 2.0 ton 5star rating hitachi A.C ,How many units it will consume in a month and per hour

66
Abhishek Jain (Mod)

A 2 ton BEE 5 star rated AC would consume about 1.8 units in an hour.

67

So if i was to use a 5 40w tubes 16 hours a day...i need to sell my vw

68

Sir i use one cfl bulb and a table fan only.
My room owner said i used 97 units in 30 days .is it possible.
I m very tensed i paid 582 rs rate for 1 unit rs 6 rupees

69
Abhishek Jain (Mod)

It is not just about 1 CFL and 1 table fan. A lot also depends on how long you use them. A 23 watts CFL plus a 75 watts fan can make up to 100 watts. And 100 watts for 10 hours can make 1 unit of electricity. But still 97 looks unreal. Unless you have more things running in the room.

70

Dear Author,
I want to Install a 1Kwp of Roof PV Solar System with battery and Inverter.
How much will it cost to me...???
How can I get subsidy and where should I approach for that.
Hoping for your kind response.
Thanks...!!!

71
Abhishek Jain (Mod)

Hi,

You can check this video. You can get some idea:

72

You said, "For appliances like Air Conditioner, Water Heater, Cloth Iron (any heating or cooling device) and pumps, this will not work". Please inform what formula works for these appliances. How to count units consumed by them.

73

hi,can you please tell me how much would 2 fans and a refrigerator would consume in 12hrs(overnight).i am using Haier 170litres fridge,which has 5 stars for power saving quality and written 264 units of consumption per year?
I have noticed that its about 3units over nights,which i feel is little high..also would UPS consume more power?

74

Hello,
This is Saptrishi Mandal need to know how to check "Earthing" in meter.

75

a work need 10amp for 10hp 440v 3phase motor, for same work 20 hp 440v 3phase motor need more than 10amp?

76
Abhishek Jain (Mod)

Well if the work can be done by 10 HP machine then by using 20 HP you are underloading the machine. The efficiency of motor is less when it is underutilized. So assuming 10 HP machine was right sized, then yes 20 HP motor will take more than 10 Amp because it will be much less efficient for doing that job.

77

What would be the cost of using an electric oven for 1 hr if the cost of unit is ₹8?

78
Abhishek Jain (Mod)

Electric Oven would be about 2 KW. So 2 units in usage of 1 hour. At Rs 8 a unit it would Rs 16.

79

Inverter continue contacted with electric.
Is it increase meter reading.

80
Abhishek Jain (Mod)

Inverters do consume electricity when kept on.

81

Trimming Beard at home is ECONOMICAL or one should go to salon

82
Abhishek Jain (Mod)

Salon is better if it is not expensive :).

83

I have Philips Trimmer using at home and Salon charges Rs. 30 for trimming beard then which one is economical ?

84
Abhishek Jain (Mod)

Using trimmer at home will be more economical.

85

Sir Whether iron (Non Steam) my clothes at home or should i give it to presswala Which one is Economical ???

86
Abhishek Jain (Mod)

Depends on how much the presswala charges you. However using iron at home in general is cheaper.

87

He Charges Rs. 4 Per Cloth and Rs. 10 per Saree then what to do ?

88
Abhishek Jain (Mod)

Ironing at home will be cheaper. But then one has to spend time to iron.

89

I am using desktop with LCD SCREEN, D-LINK WIFI ROUTER and CISCO DPC 3008 CABLE MODEM. i want to know that how much electricity (units) consumed by both modem in a month?

90
Abhishek Jain (Mod)

Hi Keshav,

Typically routers consume 4-5 watts. So their unit consumption would be (5 x 24 x 31) / 1000 = 3.72 units per month.

91

Helo there,my last month meter shows 2017 kwh and this month it shows 4114 kwh so what is the unit i have consumed and how much do i have to pay if per unit is 8Rs.
please help.
thank you

92
Abhishek Jain (Mod)

Your units consumed would be 4114 - 2017 = 2097. And at Rs 8 a unit, the cost would be Rs 16776 just for the energy charges. Along with it you would get fixed charges, fuel surcharge and electricity duty/tax.

93

Wow!!!i have to pay rs 16776 just for using 2 fans?
I don’t know whether i have given you the right kwh or not because i am not femelier with the meter.
anyway in my digital meter this was the numbers shown last month 2017 and for this month 4117.the above numbers are the only numbers shown in the meter so i hope you are geting the picture of what im saying now..
please help

94
Abhishek Jain (Mod)

If it is juts two fans then it may be that the reading would be 201.7 and 411.7. In that case your consumption is 210 units. Then at Rs 8 per unit you would get energy charges of 210x8 = Rs 1680.

Some energy meters also measure to a single decimal place of kWh.

95
Yogesh J Ingle

I like to know how can I increse the Pv cell efficiency using electronics components or devices?

96
Abhishek Jain (Mod)

Hi Yogesh,

We are not aware of it. You will have to ask this to a PV technical expert.

97

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