Electricity Calculator
Appliance Energy Cost Estimation
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Enter an appliance's wattage and usage to estimate its running cost.
Understanding Your Electricity Bill
Utilities bill electricity by the kilowatt-hour (kWh) — the energy used by a 1,000-watt device running for one hour. Knowing an appliance's wattage and how many hours a day it runs lets you estimate its slice of your monthly bill.
Watts vs. Kilowatt-Hours
Watts measure instantaneous power draw; kilowatt-hours measure energy used over time. A 100W bulb running for 10 hours uses 1 kWh — the same as a 1,000W device running for 1 hour.
The Biggest Energy Hogs
Heating, cooling, water heaters, and clothes dryers typically dominate a home's electricity bill far more than electronics or lighting.
Finding an Appliance's Wattage
Check the nameplate or manual for a listed wattage. If only amps and volts are listed, multiply them together (Watts = Volts × Amps) to get an approximate wattage.
Use a Plug-In Meter
A inexpensive plug-in power meter gives the most accurate real-world wattage, since actual draw can differ from the nameplate rating.
Key Takeaways
- Check Your Bill: Your utility bill lists your actual rate per kWh — using it here gives the most accurate estimate for your area.
- Standby Power: Many devices draw a small amount of power even when "off" — factor this in for always-plugged-in electronics.
- Tiered Rates: Some utilities charge more per kWh once you cross a usage threshold — check your rate structure for a more precise estimate.