Pick your gadgets and see what your whole setup adds or saves on your power bill. Free, no sign-up.
Whole-Home Energy Calculator
What does your smart home setup add up to?
Pick the gadgets you want from each category. You’ll see how much electricity the whole combination adds or saves each month, what that means on your bill, and how long your backup battery would last.
About your current thermostat
Want a deeper check? The Thermostat Payback calculator adds the thermostat price and any utility rebate to show how many years it takes to pay for itself.
About your driving
Want a deeper check? The EV Charger Panel Check runs a simplified version of an electrician’s load calculation to see whether your electrical panel has room for a charger.
About your smart plugs
About your solar panels
What should stay on during an outage?
Want a deeper check? The Battery Backup calculator lets you pick how long the outage lasts and matches you to the power stations that cover it.
How the math works: EV charging assumes 3 miles per kWh (most EVs get 2.5 to 3.3) plus about 14% lost while charging on Level 2, and uses your off-peak rate if you enter one. Thermostat savings use the same conservative rates as my thermostat calculator (ENERGY STAR puts the average at about 8% of heating and cooling costs), applied to 45% of your electricity in an electrically heated home, or 19% (air conditioning’s share of US home electricity) plus 45% of your gas bill in a gas-heated one. Energy monitors and smart panels count as 3% of your home’s electricity, a little under the 3.8% average that real-time feedback saved in studies reviewed by ACEEE, and only once if you pick both. An energy monitor is assumed to draw a few watts (about 2 kWh a month). Smart plug savings are the standby watts you cut times the hours switched off, minus the plug’s own draw (Emporia lists 1 W; the others don’t publish a figure, so we assume 1 W). Solar output is panel watts times peak sun hours times 0.86 (NREL’s default 14% losses), capped at your power station’s solar input; it refills the battery and isn’t counted in your bill. Appliance loads match my battery backup calculator, and battery hours use 85% of rated capacity to allow for inverter losses. These are estimates, not a quote. Your utility bill and an electrician have the final word.
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How the calculator works
Most smart home gadgets get judged one at a time. In a real home they work together: an EV charger adds to your bill, a smart thermostat and an energy monitor win some of it back, and a backup battery keeps the essentials running when the grid goes down.
Pick a product from each category you are considering, from thermostats and EV chargers to smart plugs and solar panels, or leave a category at None. The calculator adds up the whole setup: the electricity it adds or saves each month, the net change on your bill, and how long your battery would last. Every product in it is one I have reviewed.
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