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Watts = kWh × 1000 ÷ Hours
Where:
This calculation gives you the average power over the time period. Actual instantaneous power may vary. For example, a refrigerator with 900 kWh monthly usage (average 1250W) actually cycles between 0W and ~150W compressor operation.
Average watts needed to consume the given kWh over different time periods:
| kWh | 1 hour | 2 hours | 4 hours | 8 hours | 24 hours |
|---|---|---|---|---|---|
| 1 | 1000W | 500W | 250W | 125W | 42W |
| 5 | 5000W | 2500W | 1250W | 625W | 208W |
| 10 | 10000W | 5000W | 2500W | 1250W | 417W |
| 15 | 15000W | 7500W | 3750W | 1875W | 625W |
| 20 | 20000W | 10000W | 5000W | 2500W | 833W |
| 30 | 30000W | 15000W | 7500W | 3750W | 1250W |
| 50 | 50000W | 25000W | 12500W | 6250W | 2083W |
| 100 | 100000W | 50000W | 25000W | 12500W | 4167W |
| Scenario | Time Period | Avg Watts | Meaning |
|---|---|---|---|
| Monthly Electric Bill: 900 kWh | 720 hours (30 days) | 1250W | Average household power draw |
| Daily Usage: 30 kWh | 24 hours | 1250W | Typical home daily consumption |
| EV Full Charge: 60 kWh | 8 hours | 7500W | Level 2 charger power needed |
| Battery Backup: 1 kWh | 2 hours | 500W | UPS load capacity |
| Solar Daily: 20 kWh | 5 peak hours | 4000W | Solar panel system size needed |
The kWh to watts conversion determines the average power consumption in watts from a total energy measurement in kilowatt-hours over a known time period. This is the fundamental relationship between energy and power: watts represent the rate at which energy is consumed, while kilowatt-hours represent the cumulative amount of energy used. The formula is straightforward: Watts = kWh × 1,000 ÷ Hours. This conversion has practical applications across residential energy management, commercial facility operations, and renewable energy system design. Homeowners use it to understand their electricity bill in terms of average power draw, solar installers use it to size photovoltaic arrays, and facility managers use it to benchmark building energy performance measured in watts per square foot, a key metric in ASHRAE 90.1 energy standards and ENERGY STAR building certifications.
Note the kWh value from your electricity bill, smart meter, plug-in energy monitor, or solar production meter. For appliance-level analysis, use a kill-a-watt meter to measure individual devices over 24+ hours.
Convert the measurement period to hours. Common periods: 1 day = 24 hours, 1 week = 168 hours, 1 month = 720 hours (30 days), 1 year = 8,760 hours. Use exact billing period hours for the most accurate result.
Multiply kWh by 1,000 to convert to watt-hours, then divide by the number of hours. Example: 30 kWh consumed in 24 hours = 30,000 Wh ÷ 24 = 1,250 watts average power consumption.
The result is average watts. For generator sizing, multiply by 2–3 for peak capacity. For solar sizing, divide daily kWh by peak sun hours (4–6 hours) instead of 24 to get the required panel wattage.
Converting kWh to watts lets you compare actual power draw of different appliances on equal terms, helping identify the biggest energy consumers in your home or facility.
Solar and wind systems are rated in watts. Knowing your average watt consumption from kWh data is the starting point for sizing renewable energy installations to meet your needs.
Translating kWh to watts helps calculate the cost of running individual devices, enabling informed decisions about energy-efficient upgrades and usage habits.
| Appliance | Rated Watts | Daily kWh | Avg Watts (24h) | Duty Cycle |
|---|---|---|---|---|
| Refrigerator | 150W | 1.5 kWh | 63W | ~40% |
| Window AC (10,000 BTU) | 1,200W | 8.4 kWh | 350W | ~30% |
| Electric Oven | 2,500W | 2.0 kWh | 83W | ~3% (1h/day) |
| LED TV (55-inch) | 80W | 0.48 kWh | 20W | ~25% (6h/day) |
| Desktop Computer | 200W | 1.6 kWh | 67W | ~33% (8h/day) |
| EV Charger (Level 2) | 7,200W | 10 kWh | 417W | ~6% (1.4h/day) |
Divide your total monthly kWh by 720 hours (30 days × 24 hours/day). For example, a bill showing 900 kWh means your household draws an average of 900,000 Wh ÷ 720 h = 1,250 watts continuously. This is the average; your peak demand is typically 3–5 times higher during high-usage periods.
Most appliances cycle on and off rather than running continuously. A refrigerator rated at 150W only runs its compressor about 40% of the time, averaging 63W over 24 hours. A space heater with a thermostat may cycle at 50% duty, and most devices are only used for a fraction of the day.
Do not divide daily kWh by 24 hours for solar sizing. Instead, divide by your location's peak sun hours (typically 4–6 hours). If you use 30 kWh/day and get 5 peak sun hours, you need 30,000 Wh ÷ 5 h = 6,000 watts (6 kW) of solar panels, plus 20–25% for system losses.
The average watts figure provides a baseline, but generators must be sized for peak load, not average. List all appliances that may run simultaneously, sum their rated watts, and add 25% for motor starting surges. A home averaging 1,250W may need a 7,500–10,000W generator to handle peak loads.
Watts (W) and kilowatts (kW) both measure power—the rate of energy use. 1 kW = 1,000 W. Kilowatt-hours (kWh) measure energy—the total amount consumed over time. A 100-watt light bulb (0.1 kW) running for 10 hours consumes 1 kWh of energy. Your electricity bill charges per kWh consumed.