About the Electricity Cost Calculator
The Electricity Cost Calculator turns a wattage label and a daily usage pattern into the actual dollar cost of running that appliance: per day, per month, per year. It accepts wattage directly from the nameplate (or via quick presets for common appliances), multiplies by hours-of-use and days-per-week, converts to kilowatt-hours, then applies your local per-kWh rate to surface a number you can act on.
It is built for homeowners hunting the hidden cost of a space heater or pool pump, renters comparing a window AC against a portable, sustainability-curious users auditing their phantom-load problem, and small landlords pricing utility allowances. The Whole-Home Audit mode ranks every major appliance in the house by annual cost so you can see exactly where the bill is going.
Every calculation runs locally in your browser. No appliance list, usage pattern, or rate value is transmitted — the page makes no network call after first load. Nothing is logged or stored in cookies. The state-rate presets ship bundled with the JavaScript, so even your ZIP-code-level rate choice never leaves your device.
Real-world consumption rarely matches the nameplate. Motors draw a brief startup surge, heating elements modulate on a thermostat, and refrigerator compressors run only a fraction of the hour despite the always-on label. For the most accurate audit, pair this calculator with a $20 plug-in power meter (Kill A Watt or similar) on the appliance in question and use the observed weekly kWh rather than the theoretical figure.
Electricity rates typically rise 3–5% per year. See your projected costs.
How to Use the Electricity Cost Calculator
In Single Appliance mode, enter the wattage, daily usage hours, and days per week for any device. Use the common appliance pills for quick selection. In Whole Home Audit mode, add all your major appliances to see a ranked breakdown of which ones cost the most and where to save.
Understanding Watts, Kilowatts, and kWh
Watts measure instantaneous power draw. Kilowatts (kW) are just watts divided by 1,000. A kilowatt-hour (kWh) is one kilowatt used for one hour — this is what your utility bills. If a 1,500W space heater runs for 2 hours, it uses 3 kWh. At $0.16/kWh, that session costs $0.48.
The Biggest Energy Hogs in a Typical Home
HVAC systems (heating and cooling) typically account for 40–50% of a home’s electric bill. Water heaters come next at 14–18%. Clothes dryers, ovens, and space heaters draw significant wattage. By contrast, modern LED bulbs, phone chargers, and laptops are remarkably efficient. The audit mode ranks your appliances from most to least expensive so you can prioritize efficiency upgrades.
Phantom Power: The Silent Drain
Many devices draw power even when “off” — TVs, game consoles, cable boxes, and chargers left plugged in. This phantom load (also called vampire power or standby power) can add $100–$200 to your annual bill. Smart power strips that cut power when devices are off can eliminate most phantom drain.
LED vs. Incandescent: The Math
A 60W incandescent bulb running 5 hours a day costs about $17.50 per year. A 9W LED producing the same light costs about $2.60 per year. With 30 bulbs in a typical home, switching saves roughly $450 annually. LEDs also last 15–25 times longer, so the replacement cost savings add up too.
How to Read Your Electric Bill
Your bill shows total kWh consumed during the billing period. Divide the total charges (excluding fixed fees and taxes) by kWh to get your effective rate. Many utilities now offer time-of-use pricing where electricity costs more during peak hours (typically 2–7 PM weekdays) and less overnight. Pro subscribers can model TOU rates to find optimal usage schedules.
Looking for related tools? Try our Solar Savings Calculator to estimate how much you could save by switching to solar, or our Fuel Cost Calculator to plan your driving expenses. Explore all Everyday Calculator tools.
Frequently Asked Questions
What is a kilowatt-hour (kWh)?
A kilowatt-hour is one kilowatt of power used for one hour. It is the unit your utility uses for billing. A 1,000-watt appliance running for one hour consumes exactly 1 kWh, which at $0.16 costs about 16 cents.
Which household appliances use the most electricity?
Heating and cooling dominate most bills: central AC, electric furnaces, space heaters, and water heaters typically top the list. After those, electric clothes dryers, ovens, refrigerators, and pool pumps are the biggest draws in a typical US home.
How much does a space heater cost to run?
A 1,500-watt space heater running 8 hours a day costs about $1.92 per day at $0.16 per kWh, which works out to roughly $40 to $55 per month. Electric resistance heaters are one of the most expensive ways to heat a room.
Is phantom power real?
Yes. Devices on standby (TVs, cable boxes, game consoles, chargers, smart speakers) continue drawing small amounts of power around the clock. In a typical US home, phantom loads add up to roughly $100 to $200 per year, or about 5% to 10% of the electric bill.
How do I find my electricity rate?
Look at your utility bill for a line labeled "rate per kWh," "supply charge," or "energy charge." Add any per-kWh delivery charges to get the all-in rate. If your bill is confusing, divide the total dollar amount by total kWh used that month for a quick effective rate.