17 free calculators
Home energy calculators
See where your energy money goes, size heating and cooling the right way, and find out whether solar, a heat pump or a battery really pays off where you live.
Calculators
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Solar payback Savings and payback by state -
AC size BTUs for your room and climate -
Electric bill What each appliance really costs -
EV charging Home charging cost per month -
Generator size Watts to run your essentials -
Water heater size Gallons or GPM for your household -
Furnace size BTUs to heat your home -
Heat pump savings Heat pump vs furnace or baseboard costs -
Home battery Battery backup size for outages and solar -
Space heater cost What a space heater adds to your bill -
LED savings Savings from switching to LED bulbs -
Wire size Wire gauge for amps, distance and voltage drop -
Solar panels needed How many panels cover your electric use -
Dehumidifier size Pints per day for your space -
Appliance energy cost What each appliance costs to run -
Heating cost Gas vs. electric vs. propane vs. oil -
HVAC replacement cost New AC, furnace or heat pump cost
Energy guides
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Power
Are Solar Panels Worth It in 2026?
What changed when the federal tax credit ended, and when solar still pays off.
Read the guide
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Power
Heat Pump vs. Furnace
Running cost by climate and fuel, upfront price, comfort and when a hybrid system wins.
Read the guide
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Power
Tankless vs. Tank Water Heater
Hot water supply, energy use, installation cost and lifespan, with real sizing examples.
Read the guide
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Power
How to Lower Your Electric Bill
The changes that save the most, ranked by dollars per year, from free to worth the investment.
Read the guide
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Power
Portable vs. Standby Generator
Cost, power, fuel, installation and safety of the two ways to keep the lights on.
Read the guide
Start with the bill you already pay
The best energy upgrade depends on your rates, your climate and what you already have. These calculators use state-level electricity, natural gas, propane and heating oil prices from the US Energy Information Administration, and every rate can be replaced with the one on your own bill.
- Find the big users. The electric bill calculator ranks what each appliance costs per month.
- Size it right. Oversized AC units and furnaces cost more and work worse. Use the AC and furnace size calculators, then ask for a Manual J load calculation before you buy a central system.
- Check the payback. Federal tax credits for home solar, batteries, heat pumps and insulation ended for equipment installed after December 31, 2025, so the numbers have to work on their own.
- Plan for outages. Compare a generator with a home battery, and read the safety rules before you connect anything to your house.