Typical energy use by appliance and task
| Task / appliance | Typical energy per use |
|---|---|
| Full laundry wash cycle | ~0.5 – 2 kWh |
| Electric kettle (boiling ~1L) | ~0.1 – 0.15 kWh |
| EV home charging (full charge, small battery) | ~7 – 12 kWh |
| Central AC, one hour of runtime | ~1 – 3.5 kWh |
- This is a straightforward unit-conversion calculation; the accuracy of the result depends entirely on the accuracy of the wattage and hours entered.
- For appliances with variable/cycling loads, use the average running wattage over the period, not the instantaneous peak.
What is a kilowatt-hour (kWh)?
A kilowatt-hour is a unit of energy equal to the work done by a 1,000-watt (1 kW) device operating continuously for one hour. It is the standard billing unit used by electricity utilities worldwide. Because power (watts) and time (hours) both vary by appliance and use case, this calculator converts any combination of the two into a single, comparable kWh figure.
This calculator differs from the electricity cost calculator in that it computes energy and cost for a single specified duration (for example, one wash cycle or one charging session) rather than projecting a recurring daily/monthly/yearly cost.
How to use this kWh calculator
- Enter the appliance's power rating in watts, from its label or spec sheet.
- Enter the number of hours the appliance will run for this calculation.
- Enter your electricity rate per kWh from your utility bill.
- Read the total energy used in kWh and the estimated cost for that usage.
The formula behind kWh calculation
Energy in kilowatt-hours equals power in watts multiplied by hours of use, divided by 1,000. Cost equals that energy figure multiplied by the electricity rate per kWh.
Worked example: a 2,000 W appliance run for 3 hours uses 2,000 × 3 ÷ 1,000 = 6 kWh. At an electricity rate of $0.25/kWh, that usage costs 6 × $0.25 = $1.50.
Common mistakes
- Confusing watts (a rate of power) with watt-hours or kWh (a quantity of energy) — they are not interchangeable units.
- Forgetting to divide by 1,000 when converting watt-hours to kilowatt-hours.
- Using a device's maximum rated wattage instead of its typical operating wattage.
- Entering minutes instead of hours in the hours field, which inflates the result by a factor of 60.
Pertanyaan yang sering diajukan
How many kWh does a 2000W appliance use in 3 hours?
A 2,000 W appliance run for 3 hours uses 2,000 × 3 ÷ 1,000 = 6 kWh. At $0.25 per kWh, that usage would cost about $1.50.
How do I convert watts to kWh?
Multiply the power in watts by the number of hours used, then divide by 1,000. This converts watt-hours into kilowatt-hours, the standard billing unit for electricity.
What is the difference between a watt and a kilowatt-hour?
A watt measures the rate of power consumption at an instant; a kilowatt-hour measures the total energy consumed over time. A 1,000 W device uses 1 kWh for every hour it runs continuously.
How do I find my electricity rate?
Your electricity rate per kWh is listed on your utility bill as a per-unit charge, and it can vary by provider, region, and sometimes by time of day.
Referensi
- U.S. Energy Information Administration (EIA) — definition of the kilowatt-hour as the standard unit of electricity billing.
- International System of Units (SI) — watt and watt-hour unit definitions underlying the kWh conversion.