What Uses Watts in Your Home?

Electricity usage is calculated in kilowatt-hours. A kilowatt-hour is 1,000 watts led flood light used for one hour. As an example, a 100-watt light bulb operating for ten hours would use one kilowatt-hour.

1000 Watt LED Flood Light
1000 Watt LED Flood Light

When we talk about calculating our energy usage and minimizing how much electricity we consume, we usually talk about the big things: gadgets, refrigerators, dishwashers, the laundry, and so on.

But there is one way nearly everyone consumes electricity in an average day – and often multiple times at once.

How to calculate electric usage cost:

1. Volts x Amps = Watts
2. Watts ÷ 1,000 = Kilowatts (kW)
3. Kilowatts (kW) x Hours of Use = Kilowatt Hours (kWh)
4. Kilowatt Hours (kWh) x kWh rate = Cost of Usage
5. Add TVA Power Cost Adjustment charge per kWh

Below are some examples of electrical appliances found in most homes. These examples are using a 10 cents per kWh rate.

Appliance/EquipmentAvg. UsageMonthly kWhCost/Month
Comfort & Health   
Air Conditioner – Window
12,000 BTU (1,400 Watts)
8 hours/day341$34.10
Dehumidifier (257 Watts)12 hours/day94$9.40
Fan – Furnace (300 Watts)7 hours/day64$6.40
Fan – Ceiling (125 Watts)12 hours/day46$4.60
Fan – Attic (1000 Watts)2 hours/day61$6.10
Heat Pump (Average Rating)
(1,800 sq. ft. house) 7.7 HSPF*
dailyAverage Annual Cost$841.50
Heat Pump (High Efficiency)
(1,800 Sq. ft. house) 8.5 HSPF*
dailyAverage Annual Cost$762.30
Heat Pump (Geothermal)
(1,800 sq. ft. house) Equiv. 13.3 HSPF*
dailyAverage Annual Cost$487.10
Heater – Portable (1500 W)8 hours/day365$36.50
Humidifier (177 Watts)8 hours/day43$4.30
Water Heater (4500 W)3 hours/day411$41.10
Hair Dryer (1,000 W)15 min./day7.6$0.76
*Heating Season Performance Factor (an efficiency rating)
**Based on 4,296 Heating Degree Days. Cooling costs would be approximately 40% of total energy costs.
Food Prep. & Preservation  
Blender/Food Processor (400 Watts)1 hour/week2$0.20
Coffee Maker (894 Watts)one hour/day27$2.70
Dishwasher (1,200 Watts)
(excludes hot water costs)
one hour/day37$3.70
Microwave Oven (1,450 W)30 min./day22$2.20
Range (12,200 Watts)30 min./day186$18.60
Freezer 15 Cu. Ft. (341 W.)12 hrs/day124$12.40
Refrigerator – 14 Cu. Ft. (440 W.)12 hrs/day161$16.10
Refrigerator – 18 Cu. Ft.
(manual defrost – deduct 35%)
12 hrs/day180$18.00
Clothes Dryer (4,900 W)6 loads/week90$9.00
Washer (512 Watts)
(Excludes water costs)
6 loads/week9$.90
Home Entertainment/Recreation  
42″ Plasma TV (320 Watts)
(instant-on tvs use some electricity continuously)
35 hours/week44.8$4.48
Home Computer (500 W)
Including Monitor
4 hours/day61$6.10
Hot Tub (5,000 W)2 hrs/day304$30.40
Pool Heater (incl. motor)avg/daily670$67.00
Pool Pump (1 hp)continuous1240$124.00
40-Watt Bulb (40 W)
Equivalent compact fluorescent
4 hours/day
4 hours/day
60-Watt Bulb (60 W)
Equivalent compact fluorescent
4 hours/day
4 hours/day
75-Watt Bulb (75 W)
Equivalent compact fluorescent
4 hours/day
4 hours/day
100-Watt Bulb (100 W)
Equivalent compact fluorescent
4 hours/day
4 hours/day
Electric Fence Chargerdaily2$.20
Heater (tractor engine block) (600W)10 hrs/day182$18.20
Heater (livestock tank)8 hrs/daily365$36.50
Auto Battery Charger (600W)2 hours36$3.60
Well Pump (750-1000W)avg./10% usage40$4.00

How Many Watts Does a Light Bulb Use Per Hour?

As energy calculations go, this one’s easy. To find the energy usage of a light bulb and how much it will cost you, all the information you need is printed right on your light bulbs and your electric bill. First, check your light bulb’s wattage, which has a “W” at the end. This may be printed on plastic or stamped into metal. Next, check the kilowatt-hour (kWh) rate on your latest electric bill. This is the rate you pay for each kilowatt-hour of electricity.

300 watt led flood light
300 watt led flood light

Divide the bulb’s wattage by 1,000 to convert it to kilowatts. Then, multiply the bulb’s kilowatts by your kWh rate to see how much the bulb will cost you per hour.

Let’s assume your kWh rate is 12 cents and you have a 60-watt incandescent bulb. You want to calculate your 60-watt light bulb energy use and cost per hour.

  • 60 watts multiplied by one hour is 60 watt-hours of energy. Divide by 1,000 to get .06 kWh
  • .06 kWh multiplied by .12 cents is .0072 cents

So how much does it cost to run a 60-watt light bulb for 1 hour? A little more than 7/10ths of a penny at this rate. That may not sound like much, but remember, that’s just one bulb glowing for one hour. A house full of lights can add up by the end of the day.

But what if you also had an equivalent LED bulb that only uses 12 watts? 12 divided by 1,000 is .012, and .012 multiplied by .12 is .00144. At your 12-cent energy rate, you could use that 60-watt incandescent bulb for about 140 hours before it cost you a dollar, but that same dollar could keep the 12-watt LED flood light burning for nearly 700 hours.

Resources: http://www.wrecc.com/what-uses-watts-in-your-home/


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