How to Calculate the Electricity Cost of Any Appliance
I built this electricity cost calculator to make it easy to see exactly what any appliance is adding to your energy bill. The formula is simple: multiply the appliance wattage by the hours used per day to get watt-hours, divide by 1,000 to convert to kilowatt-hours (kWh), then multiply by your electricity rate. Most households in the US pay between $0.12 and $0.18 per kWh — check your latest electricity bill to find your exact rate.
The results can be surprising. A 1,500W space heater running 8 hours a day at $0.15/kWh adds about $54 to your monthly bill. A 60W laptop left on all day costs only about $2.70 per month. Understanding these numbers helps you make smarter decisions about which appliances to replace, when to run them, and whether an energy-efficient upgrade will actually pay off.
Finding the Wattage of Your Appliances
The wattage of most appliances is printed on a label on the back or bottom of the device. For devices without clear labels, here are typical wattages for common household items:
- Refrigerator: 100–400W (but only runs 30–50% of the time)
- Dishwasher: 1,200–2,400W per cycle (typically 1.2–1.5 kWh per wash)
- Washing machine: 500–1,000W; dryer: 1,800–5,000W
- Central air conditioner: 2,000–5,000W depending on tonnage
- LED light bulb: 8–15W (compared to 60W incandescent equivalent)
How to Reduce Your Electricity Bill
Once you know which appliances cost the most to run, you can target them for savings. Heating and cooling typically account for 40–50% of a home's electricity use, making them the highest-impact category. Setting your thermostat 7–10°F lower for 8 hours per day can save up to 10% annually on heating and cooling costs, according to the US Department of Energy.
Switching from incandescent to LED lighting is one of the quickest payback improvements you can make. A 10W LED replaces a 60W incandescent and lasts 15–25 times longer. If you have 20 light fixtures running 5 hours per day, switching to LED saves roughly $90 per year at $0.15/kWh — and bulbs typically pay back in a few months.
Frequently Asked Questions
How do I find my electricity rate?
Your electricity rate per kWh is listed on your monthly utility bill — look for a line that says "energy charge" or "rate per kWh." In the US, the national average is around $0.16/kWh, but rates vary significantly by state. Hawaii averages over $0.38/kWh while Louisiana averages around $0.10/kWh. Some utilities also have tiered rates where you pay more per kWh once you exceed a baseline usage level.
What is "vampire" or standby power?
Standby power is the electricity consumed by devices when they're turned off but still plugged in. TVs, game consoles, phone chargers, and cable boxes are common culprits. A typical home loses 5–10% of its electricity consumption to standby loads — that can be $50–$150 per year. Smart power strips and unplugging devices you're not using regularly are easy fixes.
Is it cheaper to run appliances at night?
It depends on whether your utility offers time-of-use (TOU) pricing. If they do, off-peak hours (typically nights and weekends) can be 30–50% cheaper than peak hours. Running your dishwasher, washing machine, and EV charger overnight on a TOU plan is a simple way to cut costs. Check your utility's website or call them to find out if TOU rates are available in your area.
