Electricity Calculator

Calculate electricity consumption and cost for any appliance. Estimate power usage, energy consumption, and electricity bills with our easy-to-use calculator.

Calculation Results

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Total Calculation Results

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Comparison Results

Appliance Daily Energy (kWh) Monthly Energy (kWh) Yearly Energy (kWh) Yearly Cost ($)
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Common Appliances Power Consumption

Common Appliances Estimated Wattage (W)
Home appliances:
Air Conditioner (HVAC) 2500-10000
Air conditioner (window unit) 1500-5000
Heater (home) 5000-20000
Heater (portable) 750-2000
Humidifier 25-350
Dehumidifier 200-750
Fan (ceiling, table) 15-200
Light bulb (LED) 3-25
Light bulb (incandescent) 15-200
Electric water heater 3000-6600
Kitchen appliances:
Refrigerator 500-1000
Electric range/oven 2000-5000
Electric cooktop/stove 750-5000
Microwave oven 750-1500
Dishwasher 1200-2000
Coffee maker 600-1200
Toaster 750-1500
Electric kettle 1000-2000
Electric cooker 160-1500
Other appliances:
Electric vehicle charger 1,500-20,000
Television 25-500
Washing machine 400-1500
Clothes dryer 1800-5000
Clothes iron 750-2000
Hair dryer 750-2000
Desktop computer 100-250
Laptop computer 35-150
Smart phone charger 5-25
Water pump/motor 750-2000

Understanding Electricity Units

One of the most common units of electrical power for appliances is the watt (W). Other common units of power include kilowatts (kW), British thermal units (BTU), horsepower (hp), and tons.

Watts, kilowatts and kilowatt-hours:

Watts (W) is a unit of power used to quantify the rate of energy transfer. It is defined as 1 joule per second. A kilowatt is a multiple of a watt. One kilowatt (kW) is equal to 1,000 watts. Both watts and kilowatts are SI units of power and are the most common units of power used.

Kilowatt-hours (kWh) are a unit of energy. One kilowatt-hour is equal to the energy used to maintain one kilowatt of power for one hour. Generally, when discussing the cost of electricity, we talk in terms of energy. Energy (E) and power (P) are related to each other through time (t):

P = E/t
E = Pt

Electricity is most often measured and paid for based on the number of kilowatt-hours used. The reason that kilowatts-hours are typically used as a measurement of energy rather than watt-hours is simply because of scale: the amount of energy a typical household in the United States uses in a year is on the order of millions of watts, so it is easier to discuss in terms of kilowatt-hours instead.

BTU and BTU/h

British thermal units (BTU) are a measurement of heat used as part of the Imperial and US customary units of measurement. It is defined as the amount of heat that is required to increase the temperature of 1 pound of water by 1 degree Fahrenheit. Heat is a type of energy, so BTU can be directly compared to other measurements of energy such as joules (SI unit of energy), calories (metric unit), and kilowatt-hours (kWh).

1 BTU = 0.2931 watt-hours
1 BTU = 0.0002931 kWh
1 kWh ≈ 3412 BTU

BTU/h, BTU per hour, is a unit of power that represents the energy transfer rate of BTU per hour. BTU/h is often abbreviated to just BTU to represent the power of appliances. For example, an AC marked with a label of 12,000 BTU actually has a energy transfer rate of 12,000 BTU per hour.

Horsepower:

Horsepower (hp) is a unit of power most commonly used to reference the output of engines or motors. There are a number of different definitions of horsepower. Two of them are mechanical horsepower and metric horsepower.

1 unit of mechanical horsepower = 745.7 watts
1 unit of metric horsepower = 735.5 watts

The term "horsepower" was developed by James Watt, who compared the output of steam engines to the power of draft horses based on how many times a horse could turn a mill wheel in an hour.

Ton:

There are many different definitions of a ton that are related to the measurement of weight. In the context of power, the "ton" refers to the ton of refrigeration. The ton of refrigeration is defined as the rate of heat transfer necessary to melt 2,000 pounds (1 short ton) of pure ice at 0°C in 24 hours. It is used mainly in the United States to describe how well refrigerators and air conditioners extract heat.

1 ton ≈ 3517 watts
1 ton ≈ 12000 BTU/h

Electricity Calculation Formulas

1. Power (Watts)

P = V × I

Where:

  • P = Power (Watts)
  • V = Voltage (Volts)
  • I = Current (Amps)

2. Energy (kWh)

E = P × t

Where:

  • E = Energy (kilowatt-hours)
  • P = Power (kilowatts)
  • t = Time (hours)

3. Electricity Cost

Cost = E × Rate

Where:

  • Rate = Electricity tariff per kWh

Energy Saving Tips

Switch to LED Bulbs

Replace older light bulbs, particularly incandescent light bulbs, with more efficient LED light bulbs. A typical incandescent light bulb requires 75 W while an LED only requires 9 W.

Install Programmable Thermostat

A large proportion of energy cost is typically due to heating/cooling. Programming a thermostat to adjust the temperature to suit your usage needs can lead to significant savings.

Unplug Idle Devices

Many appliances continue to draw power even when turned off. Unplug devices when not in use or use power strips to completely disconnect power.

Optimize Cooling

Use fans instead of air conditioning when possible. If using AC, set it to a reasonable temperature and use curtains to block sunlight.

Efficient Laundry

Wash clothes in cold water when possible and always wash full loads. Clean the lint filter in your dryer after each use to improve efficiency.

Improve Insulation

Insulate your home as best as possible. Windows, doors, vents, the attic, walls, floors, basement, and crawlspace of your home, if not well-insulated, can lead to higher heating and cooling bills.