kWh Calculator
Calculate energy consumption in kilowatt-hours (kWh) and estimate electricity costs with monthly and yearly projections.
How do I calculate kilowatt-hours (kWh)?
Formula: kWh = (Watts × Hours) ÷ 1000. Example: A 1500-watt heater running for 8 hours uses 12 kWh (1500 × 8 ÷ 1000). Common appliances: 100W light bulb for 10 hours = 1 kWh. 1000W (1 kW) device for 1 hour = 1 kWh. 2000W AC for 5 hours = 10 kWh. Your electric bill charges per kWh, typically $0.10-$0.15 per kWh. To find daily usage, multiply hours of daily use. For monthly, multiply daily kWh by 30 days.
How much does electricity cost per kilowatt-hour?
Average US electricity costs: Residential: $0.10-$0.15 per kWh (varies by state). Hawaii highest: ~$0.30/kWh. Louisiana lowest: ~$0.08/kWh. Commercial: $0.08-$0.12/kWh. Industrial: $0.06-$0.10/kWh. Peak vs off-peak: Some utilities charge more during peak hours (2-8 PM). Time-of-use plans can save money by using power at night. Check your electric bill for exact rate. Calculate monthly cost: Monthly kWh × rate. Example: 900 kWh × $0.12 = $108/month.
What appliances use the most kilowatt-hours?
High energy users (monthly kWh): Central AC: 600-1000 kWh/month ($60-150). Electric water heater: 300-500 kWh ($30-75). Electric dryer: 75-100 kWh ($8-15). Refrigerator: 50-150 kWh ($5-20). Electric oven: 40-100 kWh ($4-15). Dishwasher: 30-60 kWh ($3-9). Washer: 20-40 kWh ($2-6). TV (LED): 10-30 kWh ($1-4). Computer: 10-25 kWh ($1-3). LED lights: 5-15 kWh ($0.50-2). Biggest savings: Replace old AC, use cold water for laundry, air-dry clothes.
How do I estimate my monthly electricity bill?
Calculate total monthly kWh: 1) List all appliances with wattage. 2) Estimate daily hours of use for each. 3) Calculate daily kWh: (Watts × Hours) ÷ 1000. 4) Multiply by 30 for monthly. 5) Sum all appliances. Example: Fridge (150W, 24hrs): 4.5 kWh/day = 135/month. AC (3000W, 8hrs): 24 kWh/day = 720/month. Lights (300W, 5hrs): 1.5 kWh/day = 45/month. Total: 900 kWh/month × $0.12 = $108. Add fixed fees (~$10-20). Average household: 800-1200 kWh/month.
What is the difference between kW and kWh?
kW (kilowatt) = Power (rate of energy use). How much energy used right now. Like speed (mph). Example: 1500W heater = 1.5 kW. kWh (kilowatt-hour) = Energy (total consumption). How much energy used over time. Like distance (miles). Example: 1.5 kW × 2 hours = 3 kWh. Analogy: Water flow (kW) vs total water used (kWh). Your electric bill charges for kWh, not kW. 1 kWh = running 1 kW device for 1 hour. A 100W bulb for 10 hours uses same energy as 1000W device for 1 hour (both = 1 kWh).
How can I reduce my kWh usage and save money?
Top energy-saving strategies: 1) AC/Heating: Set thermostat 2-3°F higher (summer) or lower (winter) = 10-15% savings. Use fans, programmable thermostat. 2) Water heater: Lower to 120°F, use less hot water, insulate tank. 3) Appliances: Unplug when not in use (phantom load = 5-10% of bill). Use Energy Star appliances. 4) Lighting: Switch to LEDs (75% less energy). Turn off lights. 5) Laundry: Cold water wash, air dry. 6) Peak hours: Run appliances during off-peak times. 7) Insulation: Seal leaks, add insulation. Potential savings: 20-30% ($20-50/month).
How do I calculate yearly energy costs from kWh?
Yearly cost calculation: 1) Calculate daily kWh: (Watts × Daily Hours) ÷ 1000. 2) Multiply by 365 days. 3) Multiply by electricity rate. Example: 1000W space heater, 6 hours/day, $0.12/kWh. Daily: 1000 × 6 ÷ 1000 = 6 kWh. Yearly: 6 × 365 = 2190 kWh. Cost: 2190 × $0.12 = $262.80/year. Another example: 200W gaming PC, 5 hours/day. Daily: 1 kWh. Yearly: 365 kWh × $0.12 = $43.80. Compare appliances before purchase: Energy Star label shows yearly kWh and estimated cost.