Electricity Units: kWh, Watts, Amps, Volts
Understand kWh, watts, amps, and volts. Learn to read your electric bill, calculate appliance costs, and reduce energy use.
The Four Key Electricity Units
Understanding these four units helps you read your electric bill, compare appliances, and save money.
Volts (V) — Electrical Pressure
Voltage is the "pressure" that pushes electricity through wires. In most countries, household outlets provide either 110-120V (North America, Japan) or 220-240V (Europe, Asia, Australia).
Amps (A) — Electrical Flow
Amperage measures how much electricity is flowing. Higher amps mean more current. A typical household circuit is rated for 15-20 amps.
Watts (W) — Power
Watts measure the rate of energy consumption. The formula is simple:
Watts = Volts x Amps
A 120V outlet delivering 10 amps provides 1,200 watts of power.
Kilowatt-hours (kWh) — Energy
This is what you pay for. One kWh = 1,000 watts used for one hour.
kWh = (Watts x Hours) / 1,000
Common Appliance Power Usage
| Appliance | Typical Watts | Daily kWh (est.) |
| LED light bulb | 10W | 0.1 |
| Laptop | 50W | 0.4 |
| Desktop computer | 200W | 1.6 |
| Refrigerator | 150W | 1.5 |
| Washing machine | 500W | 0.5 |
| Air conditioner | 1,500W | 6.0 |
| Electric oven | 2,500W | 2.5 |
| EV charger (Level 2) | 7,700W | 30.0 |
| Hair dryer | 1,800W | 0.3 |
How to Read Your Electric Bill
Your electric bill charges per kWh. The average electricity rate varies globally:
- USA: ~$0.16/kWh
- UK: ~$0.34/kWh
- Germany: ~$0.40/kWh
- Australia: ~$0.30/kWh
- Switch to LED bulbs — use 75% less energy than incandescent
- Unplug vampire loads — chargers and standby devices waste 5-10% of household energy
- Use a smart thermostat — can reduce heating/cooling costs by 10-15%
- Run appliances off-peak — many utilities offer cheaper night rates
To estimate monthly cost for any appliance: (Watts x Hours/day x 30) / 1,000 x Rate
For example, running a 1,500W space heater 8 hours/day: (1500 x 8 x 30) / 1000 x $0.16 = $57.60/month
Energy Saving Tips
Convert between energy units with our Energy Converter — instantly convert kWh, joules, calories, BTU, and more.
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Andrew
·Founder of ConvertzBuilding free, accurate conversion tools for everyone. All content is AI-assisted and editorially reviewed for accuracy. Learn more about Convertz
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