About WattSums
WattSums answers one question about home energy: what does it cost where I live?
Pick your state and you get the cost of running a space heater, an air conditioner or a fridge, of heating your home with a heat pump or a furnace, of charging an EV, or how long solar panels take to pay off. Every result uses your state's average electricity rate from the U.S. Energy Information Administration (EIA), or the rate from your own bill if you type it in.
What makes it different
- Your state, not a national average. Electricity costs more than three times as much in some states as in others, so one national number can be far off. Every calculator starts from your state's rate and shows the month the data is from.
- Your bill, if you want. State averages are a starting point. Type the rate from your bill and every result updates. The rate you type stays on your device.
- The math, shown. Every calculator explains its formula, its assumptions and a worked example, so you can check the answer by hand.
The calculators
- Electricity cost calculator: cost to run any appliance, by hour, day, month and year
- Electric bill calculator: your monthly bill by appliance vs your state average
- Space heater calculator: heating one room vs the whole house
- AC cost calculator: air conditioner cost per hour and per summer month
- EV charging calculator: cost per charge, per month and per mile vs gasoline
- Watts to amps calculator: convert watts, amps, volts, kwh and dollars
- Electricity rates by state: the average rate, trend and bill in all 50 states and DC
See how we calculate for the formulas and data sources behind every number.
Estimates, not guarantees
Results are estimates for planning. Your real bill depends on your utility's plan, fixed monthly charges, time-of-use pricing and how you use each appliance. For solar or heating system decisions, get quotes from local installers before you buy.
Get in touch
Spotted a mistake, or want a calculator we don't have yet? Email hello@wattsums.com or use the contact page.