kW to kWh Calculator

About the kW to kWh Calculator

A kW to kWh calculator converts power in kilowatts to energy in kilowatt-hours by multiplying by the number of hours of operation — the fundamental energy calculation underlying every electricity bill, appliance cost estimate, and renewable energy analysis. Power (kW) is the rate of energy consumption; energy (kWh) is the total amount consumed over time. This distinction is critical: a 3 kW appliance does not consume 3 kWh until it has run for exactly one hour. Run it for 30 minutes and it uses 1.5 kWh; run it for 8 hours and it uses 24 kWh. Your electricity bill charges you per kWh of energy consumed — not per kW of power drawn. Our kW to kWh calculator handles any combination of power and time, and also calculates the electricity cost at your specified rate, making it immediately practical for homeowners evaluating appliance running costs, solar energy production estimates, battery storage sizing, and electric vehicle charging cost calculations. It works for any electrical device anywhere in the world.

How It Works

kWh = kW × Hours. This is simply power multiplied by time. Energy (kWh) = Power (kW) × Duration (hours). Cost = kWh × rate per kWh. Example 1 (air conditioner): 1.5 kW AC running 8 hours. kWh = 1.5 × 8 = 12 kWh. At $0.13/kWh: cost = 12 × $0.13 = $1.56/day or approximately $46.80/month (30 days). Example 2 (EV charging): 7.2 kW Level 2 charger running 4 hours. kWh = 7.2 × 4 = 28.8 kWh added to battery. At $0.13/kWh: $3.74 per charge session. Example 3 (solar production): 5 kW solar array producing at average 4 peak sun hours daily. kWh = 5 × 4 = 20 kWh/day = 600 kWh/month. Monthly bill offset: 600 kWh × $0.15/kWh = $90/month saved.

Tips & Best Practices

• ✓Peak sun hours for solar: solar panels produce rated kW output only at "standard test conditions" (1,000 W/m² irradiance). The daily kWh production = rated kW × peak sun hours for your location. US averages: Phoenix AZ = 5.5 peak hours, Seattle WA = 3.5, Miami FL = 5.0, New York = 4.2.
• ✓Battery sizing: to store enough energy for overnight use from daytime solar, calculate your evening/night consumption in kWh and match it to battery capacity. A 10 kWh battery (e.g., Tesla Powerwall 2 = 13.5 kWh) is sized to handle typical US overnight consumption of 8-12 kWh.
• ✓EV range from kWh: most EVs consume 0.25-0.35 kWh/mile. Adding 10 kWh to a battery provides 28-40 miles of range depending on the vehicle. A 7.2 kW Level 2 charger running 4 hours adds 28.8 kWh = approximately 82-115 miles of range.
• ✓Demand charges vs energy charges: your utility bill likely has two components — energy (kWh × rate) and potentially demand (peak kW × demand rate for commercial accounts). This calculator focuses on the energy component; demand charges require tracking peak kW not total kWh.

Who Uses This Calculator

Homeowners calculating the daily, monthly, and annual running cost of specific appliances. Solar system owners projecting energy production from panel array kW rating and local sun hours. EV owners calculating charging cost per session and monthly electricity cost increase. Battery storage designers sizing systems to store specific kWh of daily solar production. Energy managers tracking appliance consumption for efficiency programs.