Power Consumption Calculator | kWh per Day/Month/Year
Calculate electrical energy consumption in kWh. Enter device wattage and hours of use to get daily, monthly, and annual power consumption.
How to Use
- Enter the device power rating in watts (W) — found on the product label or specifications.
- Enter the average number of hours the device is used per day.
- Optionally adjust the days per month (default 30).
- Click 'Calculate' to see daily, monthly, and yearly energy consumption in kWh.
- Add multiple devices to calculate total household or workshop consumption.
- Formula: kWh = Watts × Hours / 1000. One kWh = one unit of electricity on your bill.
About Power Consumption
What is a kWh?
A kilowatt-hour (kWh) is the unit of energy used by electricity meters. One kWh = 1000W running for 1 hour = the energy used by a 100W light bulb running for 10 hours. Electricity bills charge per kWh (also called a 'unit'). In most countries, residential electricity costs between $0.05 and $0.30 per kWh. Understanding kWh helps you identify which appliances consume the most energy.
Typical Appliance Power Ratings
Common appliance power ratings: LED bulb 5–15W, incandescent bulb 40–100W, ceiling fan 30–75W, desktop computer 150–300W, laptop 30–70W, microwave 600–1500W, electric kettle 1500–3000W, washing machine 500–2500W, air conditioner 700–3500W, electric water heater 1500–4000W. High-wattage appliances used daily (air conditioners, water heaters) dominate electricity bills.
Standby Power Consumption
Most electronic devices consume power even when 'off' or in standby mode. Typical standby power: TV 0.5–3W, set-top box 10–20W, desktop computer 5–20W, phone charger 0.1–0.5W, microwave 2–5W. While individual standby draws are small, the total across all devices in a home can represent 5–10% of the electricity bill. Smart power strips and smart plugs can eliminate standby waste.
Reducing Energy Consumption
Key strategies: replace incandescent bulbs with LEDs (75% energy saving), use inverter air conditioners and refrigerators (30–50% saving), set correct thermostat temperatures, unplug chargers and devices when not in use, use Energy Star certified appliances, install smart meters to track real-time consumption. Reducing consumption by 20% through efficiency measures typically saves hundreds of dollars annually.
Key Features
- Calculates kWh consumption per day, month, and year
- Multi-device mode for total household calculation
- Simple formula: kWh = W × hours / 1000
- Customizable days per month setting
Common Applications
- Estimating electricity costs before purchasing appliances
- Identifying high-consumption devices in the home
- Energy audit for residential and commercial buildings
- Sizing solar panel systems for load coverage
- Industrial equipment energy reporting