How to calculate electricity cost
Utilities bill you in kilowatt-hours (kWh). Multiply the appliance's watts by the hours it runs, divide by 1,000 to get kWh, and multiply by your rate. For devices that cycle on and off, such as refrigerators and A/C units, use the average power or the Energy Guide label's yearly kWh.
kWh per day = Watts × Hours ÷ 1,000
Cost = kWh × Price per kWh
Example: 1,500 W space heater, 8 hours a day
1,500 × 8 ÷ 1,000 = 12 kWh per day. At $0.17/kWh that is $2.04 a day, $61.20 a month or about $745 a year.
Typical appliance power
| Appliance | Watts | Typical use |
|---|---|---|
| LED bulb | 8–10 | 5 h/day |
| Wi-Fi router | 10–20 | 24 h/day |
| Gaming PC | 300–600 | 4 h/day |
| Window A/C | 900–1,400 | 8 h/day (summer) |
| Space heater | 1,500 | 6–8 h/day (winter) |
| Electric dryer | 4,000–5,000 | 1 h per load |
Frequently asked questions
How much does it cost to run a 1,500 watt heater?
About $0.26 per hour at $0.17/kWh, or roughly $60 a month at 8 hours a day.
Where do I find my electricity rate?
Divide the energy charges on your bill by the kWh used. Include delivery charges for the true cost per kWh.
Does standby power matter?
Yes. Devices on standby can add 5–10% to a household bill.