Electricity Calculator
Calculate the electricity cost of any appliance based on wattage, hours of use and your kWh rate.
How to use the Electricity Calculator
- Enter your inputs into the Electricity Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The electricity cost formula
kWh used = (Watts × Hours) / 1000 · · · Cost = kWh × Rate
Convert appliance wattage to kilowatts, multiply by hours of use, multiply by your utility rate. Most US utilities bill in cents per kWh, typically 10–30¢ depending on region.
Worked example
A 100 W lamp running 5 hours/day for 30 days: (100 × 5 × 30)/1000 = 15 kWh. At $0.15/kWh: $2.25/month. A 1500 W space heater running 8 hours/day: 1500 × 8 × 30/1000 = 360 kWh = $54/month.
Frequently asked questions
What's my actual kWh rate?
Check your utility bill. US average in 2026 is about $0.16/kWh. Hawaii is highest (~$0.45/kWh), Washington and Louisiana among the lowest (~$0.10–$0.12/kWh).
Are appliance wattage labels accurate?
Maximum wattage is typically labeled. Actual draw varies — refrigerators cycle on/off; computers vary with load. Smart plugs and energy monitors give real-world numbers.
What's the biggest energy waste in homes?
Heating and cooling (~50% of bills in extreme climates), water heating (~14%), and electric resistance space heaters used as primary heat (very expensive vs. heat pump or central system).