Convert watts to kilowatt-hours, calculate electricity cost, and estimate energy usage. See daily, monthly, and yearly breakdowns with unit conversions and cost comparisons.
The kilowatt-hour (kWh) is the fundamental unit on your electricity bill — understanding it is the key to managing your energy costs. Every appliance, light, and device in your home consumes energy measured in kWh, and your utility charges you a specific rate per kWh. This guide demystifies the kWh and teaches you to calculate energy use and cost for any device or your entire home.
| Appliance | Watts | Typical Use | kWh/Month | Cost/Month |
|---|---|---|---|---|
| Central AC | 3,000 | 8 hrs/day | 720 | $115 |
| Electric Water Heater | 4,500 | 3 hrs/day | 405 | $65 |
| Refrigerator | 150 avg | 24 hrs/day | 108 | $17 |
| Washer + Dryer | 5,000 | 1 hr/day | 150 | $24 |
| TV (55") | 100 | 5 hrs/day | 15 | $2.40 |
| LED Bulb | 10 | 8 hrs/day | 2.4 | $0.38 |
| Desktop Computer | 200 | 8 hrs/day | 48 | $7.68 |
| EV Charging (Level 2) | 7,200 | 4 hrs/day | 864 | $138 |
Your bill has several components: energy charge (kWh × rate, the largest portion), delivery/distribution charge (fee for grid infrastructure), fixed charges (customer service fee, meter fee), and taxes. The average US household uses about 886 kWh per month at an average rate of $0.16/kWh, resulting in a typical bill of $142 before fees and taxes. HVAC (heating, ventilation, AC) typically accounts for 40-50% of energy use.
The biggest savings come from targeting your largest energy consumers. HVAC: every degree of thermostat adjustment saves 3% on heating/cooling costs. Water heater: lowering from 140°F to 120°F saves 6-10%. Lighting: switching all bulbs to LED saves 75% of lighting energy. Appliances: ENERGY STAR appliances use 10-50% less energy than standard models. Behavioral changes: turning off unused devices, using smart power strips, running dishwasher/laundry during off-peak hours.