How to calculate electricity cost
- Convert watts to kilowatts: divide by 1,000.
- Multiply by hours of use to get kilowatt-hours (kWh).
- Multiply kWh by your rate per kWh.
A 1,500 W space heater running 6 hours a day uses 1.5 × 6 = 9 kWh. At $0.18 per kWh, that’s $1.62 a day — about $49 a month.
Find your electricity rate
Your bill shows the price per kWh — divide the energy charges by the kWh used for your true rate, including delivery fees. Rates vary widely: in the US, the average residential price is in the high teens of cents per kWh, with states like Hawaii and California far higher. UK and Australian rates are typically higher still. Use your own rate for an accurate answer.
Typical appliance wattage
| Appliance | Typical watts |
|---|---|
| LED bulb | 8–12 W |
| Laptop | 30–100 W |
| TV (LED) | 50–150 W |
| Refrigerator (average) | 100–200 W (cycles on and off) |
| Gaming PC | 300–600 W under load |
| Window AC | 500–1,500 W |
| Space heater | 1,500 W |
| Clothes dryer | 2,000–5,000 W |
Wattage is printed on the device label or charger. Appliances with thermostats (fridges, AC, heaters) don’t run at full power all the time, so real use may be lower. A plug-in energy meter gives exact numbers.
Ways to lower your bill
- Heating and cooling are usually the biggest costs — a programmable thermostat helps.
- Switch to LED bulbs and unplug devices with standby power.
- Run dryers, dishwashers and EV charging during off-peak hours if your utility offers time-of-use rates.
Comparing an EV with a gas car? See trip costs with the fuel cost calculator.
Frequently asked questions
How much does it cost to run a 1500 watt heater?
At $0.18 per kWh, about $0.27 per hour, or $1.62 for 6 hours.
How do I convert watts to kWh?
Multiply watts by hours of use and divide by 1,000.
What is a kilowatt-hour?
The energy used by a 1,000-watt device running for one hour.
How do I find my price per kWh?
Check your electricity bill — divide total energy charges by the kWh used.