Electricity Calculator
Use the tool below to approximate your electricity consumption and related expenses based on each appliance’s power draw and how long it runs. Because usage patterns differ widely between homes, fine‑tune the values for each device to match your own habits for the most accurate estimate.
Units of electricity:
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:
A watt (W) measures power, indicating how quickly energy is transferred—equivalent to one joule each second. A kilowatt (kW) equals one thousand watts. Both are SI power units and are commonly used. Energy, on the other hand, is expressed in kilowatt‑hours (kWh); one kWh represents the amount of energy needed to sustain a one‑kilowatt load for one hour. When we talk about electricity costs we usually refer to energy. Power (P) and energy (E) are linked through the time they act (t):
P = E/t
E = Pt
Electric utilities typically bill customers based on the total kilowatt‑hours consumed. We prefer kWh over watt‑hours because the numbers become more manageable: a typical American household uses energy on the order of millions of watt‑hours annually, so expressing it in kWh simplifies the discussion.
BTU and BTU/h
The British thermal unit (BTU) quantifies heat in the Imperial and US customary systems. It equals the heat needed to raise the temperature of one pound of water by one degree Fahrenheit. Since heat is a form of energy, BTU can be compared directly with joules (SI), calories (metric), and kilowatt‑hours (kWh).
1 BTU = 0.2931 watt-hours
1 BTU = 0.0002931 kWh
1 kWh ≈ 3412 BTU
BTU per hour (BTU/h) is a power unit that describes how many BTU of heat are transferred each hour. In practice the abbreviation BTU often stands for BTU/h when referring to the power rating of equipment. For instance, an air‑conditioner labeled as 12,000 BTU actually delivers a heat‑transfer rate of 12,000 BTU every hour.
Horsepower:
Horsepower (hp) is a commonly used power unit, especially for engines and motors. Several definitions exist; the most familiar 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:
In power terminology, “ton” usually means a ton of refrigeration. This unit is defined as the heat‑removal rate required to melt two thousand pounds (one short ton) of ice at 0 °C within a 24‑hour period. It is predominantly used in the United States to rate the capacity of refrigerators and air‑conditioners.
1 ton ≈ 3517 watts
1 ton ≈ 12000 BTU/h
Amount of energy used by common appliances:
The table below lists typical energy demands for a range of household appliances (values can vary widely by model). Note that the figures printed on a product’s label generally represent its maximum power draw; in everyday use the actual consumption is usually far lower, so you can’t simply multiply the rated power by time to obtain the true energy use.
| 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 |
Energy saving tips:
Here are several suggestions for reducing energy consumption and cutting your electricity bill. While not every tip may suit your situation, adopting a few can still generate noticeable savings.
- Track how you use energy in your daily routine. Many people overlook their consumption patterns, but consciously noting habits over weeks can reveal where electricity is going. Simple actions—switching off unused lights or devices, using a fan instead of air‑conditioning when feasible, wearing extra layers to lower heating, hand‑drying, or running smaller loads of laundry and dishes—can add up to meaningful savings.
- Swap out the old incandescent bulbs for LED alternatives. While a typical tungsten lamp draws about 75 W, an LED of comparable brightness needs only around 9 W. Although LEDs have a higher upfront price, switching any remaining incandescents will pay off with lower electricity bills over time.
- Consider adding a programmable thermostat. Heating and cooling usually make up the biggest chunk of your power bill, so setting the thermostat to match your daily routine can trim costs. You don’t need a fancy smart model; even a basic unit can be adjusted manually to suit your schedule.
- When you’re choosing new appliances, look for energy‑efficient models. An appliance that uses less power may cost a bit more initially, but the savings on your utility bill over the years will outweigh that difference.
- Inspect your windows for drafts. In chilly climates, replacing single‑pane or poorly sealed windows with high‑performance glazing reduces heat loss. In hot areas, reflective or low‑emissivity glass and shading devices such as curtains or blinds keep solar heat out, lowering cooling expenses.
- Make sure your house is well insulated—seal gaps around doors, windows, vents, and reinforce insulation in the attic, walls, floors, and basement. Good insulation cuts both heating and cooling costs.