Audit any appliance in seconds: watts times hours per day gives annual kWh, annual cost, and how big a slice of an average US home’s 10,500 kWh it eats.
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FORMULA USEDHome Energy Audit Calculator
The one formula every audit uses
Every energy audit, from a $20 plug meter to a professional blower-door test, starts from the same arithmetic: watts × hours ÷ 1,000 = kilowatt-hours, and kilowatt-hours × your rate = cost. Annualizing means multiplying hours by 365. This calculator applies that formula to any appliance so you can rank what deserves an upgrade first.
Where the money actually goes
An average US home consumes about 10,500 kWh and spends roughly $1,500 a year on electricity. Heating and cooling dominate (often 40–50% of the total), followed by water heating, refrigeration, and always-on electronics. A single always-on device drawing 10 W costs about $11 a year — trivial alone, meaningful across a dozen of them.
Using the ranking to act
Run each suspect appliance through the calculator and sort by annual cost. Replace or reprogram the top of the list first: raising an AC schedule, killing phantom loads with power strips, and swapping remaining incandescents for LEDs usually beat buying new hardware.
Worked example
A 1,200 W space heater running 5 hours a day at $0.13/kWh.
Cost: 2,190 × $0.13 = $285 per year, about $23.70 per month.
That single heater is 21% of an average US home’s annual electricity.
How to use it
Find the appliance’s wattage on its label, manual, or a plug-in power meter.
Estimate honest hours per day — always-on devices are the ones that surprise.
Enter your utility rate from a recent bill (the US average is near $0.15–0.17).
Compare the annual cost against the 10,500 kWh average-home rows.
Frequently asked questions
How do I calculate an appliance’s electricity cost?
Multiply its watts by daily hours, divide by 1,000 to get kWh, multiply by 365 for the year, then multiply by your rate per kWh. A 1,500 W device run 3 hours daily costs roughly $200 a year at $0.13.
What are the biggest energy wasters in most homes?
Heating and cooling lead by a wide margin, then water heating and refrigeration. Among smaller loads, always-on electronics, old set-top boxes, and spare freezers in garages are classic offenders.
What is phantom energy consumption?
It is the power devices draw while switched off or idle — typically 1–10 W each for chargers, TVs, and consoles. Individually small, a household full of them can add $50–100 a year.
How accurate is nameplate wattage?
It states the maximum draw, so it overstates devices that cycle or idle, like refrigerators and laptops. For those, a cheap plug-in meter that logs kWh over a day gives the true number.
How much does the average US home use?
About 10,500 kWh of electricity per year, roughly $1,500, with wide variation by climate, home size, and heating type. All-electric homes run substantially higher.