kW to kWh Calculator
Convert kilowatts (power) to kilowatt-hours (energy) by multiplying by run-time in hours. Live calculator with daily and monthly examples.
Common conversions
| Input | Result |
|---|---|
| 1 kW × 1 h | 1 kWh |
| 0.06 kW × 24 h | 1.44 kWh |
| 0.1 kW × 24 h | 2.4 kWh |
| 1.5 kW × 8 h | 12 kWh |
| 2 kW × 3 h | 6 kWh |
| 5 kW × 4 h | 20 kWh |
| 7.4 kW × 8 h | 59.2 kWh |
| 10 kW × 1 h | 10 kWh |
The math behind it
- kWh = 3.2 × 5.5
- kWh = 17.6
Everything you need to know
A kilowatt-hour (kWh) is the energy delivered by 1 kW of power sustained for 1 hour. It's the unit your utility bills you on, while the kW rating on an appliance's nameplate only tells you how hard it pulls at any given instant.
Power versus energy: speed versus distance
Think of kW as speed and kWh as distance traveled. A car going 60 mph for 2 hours covers 120 miles, the same way a 2 kW heater running for 3 hours uses 6 kWh. Two appliances can have very different kW ratings yet use the same kWh if the lower-power one simply runs longer. A 100 W bulb left on for 24 hours uses the same 2.4 kWh as a 2,400 W space heater running for 1 hour.
How utilities bill you for kWh
Residential electric bills are almost always calculated from total kWh consumed during the billing period, multiplied by a per-kWh rate. Commercial and industrial accounts often add a separate demand charge based on peak kW, which rewards spreading load out over time rather than running everything at once. Knowing both numbers, energy in kWh and peak demand in kW, lets you understand which part of your bill each habit actually affects.
Solar production example
Solar arrays are rated in kW (DC panel capacity or AC inverter capacity), but what actually offsets your bill is kWh produced. Multiply the array's kW rating by the site's average peak-sun hours per day to estimate daily kWh output, then subtract system losses of roughly 14-22% from inverter conversion, wiring, and panel soiling. A 6 kW array in a location with 5 peak-sun hours produces roughly 30 kWh per day before losses, closer to 24-26 kWh after them.
Common applications
Multiply each appliance's kW by its hours of use to project daily kWh and forecast a monthly bill before it arrives.
If a critical load draws 0.5 kW continuously and you want 8 hours of runtime, you need 4 kWh of usable storage, plus extra headroom for depth-of-discharge and inverter losses.
A 60 kWh EV battery on a 7.4 kW Level 2 charger needs about 8 hours to fully charge (60 ÷ 7.4), a starting point before accounting for charging curve tapering near a full battery.
A 6 kW rooftop array with 5 peak-sun hours a day produces roughly 30 kWh before losses, close to 24-26 kWh after typical system derates, useful for sizing an array against a household's annual kWh usage.
Common mistakes
They measure different things, power versus energy. Saying an appliance 'uses 2 kW per hour' conflates the two; it uses 2 kW, and that equals 2 kWh only after a full hour of runtime.
Appliances cycle on and off. Multiplying nameplate kW by 24 hours overstates true daily kWh; use a measured duty cycle or smart-plug data for an accurate figure.
A 5 W device left plugged in year-round uses about 44 kWh annually, small per hour but real once multiplied out. Phantom loads across a house commonly add up to several hundred kWh a year.
Multiplying panel kW by sun-hours alone overstates production. Inverter efficiency, wiring losses, and soiling typically cut real kWh output by 14-22% from the raw calculation.
Frequently asked questions
Is kW the same as kWh?+
No. kW is power, a rate of energy flow measured at an instant. kWh is energy, the total amount used over time. A 2 kW heater is always 2 kW while it runs, but the kWh it uses keeps climbing the longer it stays on.
How much does 1 kWh cost?+
In the US, residential electricity averaged around $0.17/kWh in 2025, though rates range from roughly $0.11/kWh in some states to over $0.30/kWh in others.
How many kWh does an average house use per day?+
About 28-30 kWh per day, based on typical US residential usage of roughly 10,500 kWh per year. Usage varies widely with climate, home size, and whether the home uses electric heat.
How do I convert kW to kWh for solar panels?+
Multiply the array's kW rating by the number of peak-sun hours it receives. A 5 kW system with 5 peak-sun hours produces about 25 kWh per day before accounting for system losses.
Do system losses affect the kW to kWh conversion for solar?+
Yes. Inverter conversion, wiring resistance, and panel soiling typically reduce real-world output by 14-22% compared to the ideal kW × hours calculation, so actual kWh production runs lower than the raw formula suggests.
Is kWh always a bigger number than kW?+
Only when the run time is longer than 1 hour. At exactly 1 hour of runtime, kW and kWh are numerically equal; below 1 hour, kWh is the smaller number.
How do I estimate an appliance's monthly kWh?+
Multiply its wattage divided by 1,000 by its daily hours of use, then multiply by 30. A 1.2 kW window AC run 6 hours a day uses about 216 kWh a month.
What's the difference between the kW and kWh figures on my utility bill?+
kWh is the energy charge, your total consumption for the billing period. kW, if it appears, is a demand charge based on your highest sustained draw, common on commercial accounts but rare on residential bills.
Does a higher kW appliance always use more kWh?+
No. A high-kW appliance used briefly can use less energy than a low-kW appliance left running for hours. Total kWh depends on both power and duration, not power alone.