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E(kWh) = P(kW) × t(hours)
Where:
kW (kilowatts) measures power - the rate of energy consumption at any moment. kWh (kilowatt-hours) measures energy - the total amount consumed over time. Think of kW as speed and kWh as distance traveled.
| Appliance | Power (W) | Typical Hours | Daily kWh |
|---|---|---|---|
| LED Light Bulb | 10 W | 5 hrs | 0.05 kWh |
| Laptop | 50 W | 8 hrs | 0.40 kWh |
| Desktop Computer | 200 W | 8 hrs | 1.60 kWh |
| Refrigerator | 150 W | 24 hrs | 3.60 kWh |
| Air Conditioner (1 ton) | 1000 W | 8 hrs | 8.00 kWh |
| Electric Heater | 1500 W | 4 hrs | 6.00 kWh |
| Washing Machine | 500 W | 1 hrs | 0.50 kWh |
| Microwave | 1000 W | 0.5 hrs | 0.50 kWh |
| Electric Oven | 2000 W | 1 hrs | 2.00 kWh |
| Hair Dryer | 1500 W | 0.25 hrs | 0.38 kWh |
Converting kilowatts (kW) to kilowatt-hours (kWh) is the process of calculating how much total energy an electrical device or system consumes over a given period of time. Kilowatts measure instantaneous power – the rate at which energy is being used at any moment. Kilowatt-hours, on the other hand, measure cumulative energy – the total amount of electricity consumed over time. This distinction is critical for understanding electricity bills, sizing solar panel systems, selecting battery storage capacity, and managing energy efficiency in homes and businesses. The conversion is straightforward: multiply the power rating in kW by the number of hours the device operates. For example, a 2 kW space heater running for 3 hours consumes 6 kWh of energy. Utility companies charge customers based on kWh consumed, making this conversion one of the most practical calculations in everyday electrical engineering and household energy management.
Find the power consumption in kilowatts (kW) on the appliance label or specification sheet. If the rating is in watts, divide by 1,000 to convert to kW. For example, 1,500 W = 1.5 kW.
Decide how long the device will run in hours. If you know minutes, divide by 60. For daily calculations, estimate typical daily usage hours. For monthly, multiply daily hours by 30.
Use the formula: Energy (kWh) = Power (kW) × Time (hours). For example, a 1.5 kW heater running for 4 hours uses 1.5 × 4 = 6 kWh of energy.
Multiply the kWh result by your electricity rate to find the cost. If your rate is $0.15/kWh and you used 6 kWh, the cost is 6 × $0.15 = $0.90.
Understanding kWh consumption helps you predict and control your monthly electricity costs by identifying which appliances use the most energy.
Converting kW to kWh is essential for sizing solar panel systems and battery storage to match your actual energy consumption needs.
Tracking kWh helps you compare appliance efficiency, reduce carbon footprint, and make smarter decisions about energy usage in your home or business.
| Power (kW) | 1 Hour (kWh) | 4 Hours (kWh) | 8 Hours (kWh) | 24 Hours (kWh) |
|---|---|---|---|---|
| 0.5 kW | 0.5 | 2.0 | 4.0 | 12.0 |
| 1.0 kW | 1.0 | 4.0 | 8.0 | 24.0 |
| 1.5 kW | 1.5 | 6.0 | 12.0 | 36.0 |
| 2.0 kW | 2.0 | 8.0 | 16.0 | 48.0 |
| 3.0 kW | 3.0 | 12.0 | 24.0 | 72.0 |
| 5.0 kW | 5.0 | 20.0 | 40.0 | 120.0 |
| 7.5 kW | 7.5 | 30.0 | 60.0 | 180.0 |
| 10.0 kW | 10.0 | 40.0 | 80.0 | 240.0 |
Yes. If you know the total energy in kWh and the time period in hours, divide kWh by hours to get kW. For example, 10 kWh over 5 hours equals 2 kW of average power.
Solar panels are rated in kW because that describes their peak power output at any instant. Batteries are rated in kWh because they store a total amount of energy that can be drawn over time.
The average US household uses about 30 kWh per day, which adds up to roughly 900 kWh per month. This varies significantly by region, climate, and household size.
Not necessarily. A 2 kW heater running for 1 hour uses 2 kWh, while a 0.5 kW appliance running for 10 hours uses 5 kWh. Total energy depends on both power and time.
The average cost of 1 kWh in the United States is approximately $0.16, but rates vary widely by state and utility provider, ranging from about $0.10 to over $0.30 per kWh.