Electricity Cost Calculator
Electricity is billed by the kilowatt-hour: one kilowatt drawn for one hour. Divide an appliance’s wattage by 1000, multiply by the hours you run it, and multiply by your rate — that is the whole calculation, and it is what this tool does across a day, a month, and a year.
- Accurate
- Real-time
- Easy to use
- 100% free
Cost per month
$20.40
Cost per year
$245
Details
Updates as you typeCheck the rating plate or manual. 1 kW = 1000 W.
Take your bill total divided by the kWh billed, so it includes fixed charges.
Summary
Cost per month
$20.40
- Cost per day
- $0.68
- Cost per year
- $245
- kWh per month
- 120.0 kWh
- kWh per year
- 1,440 kWh
- Cost per running hour
- $0.17
- Yearly figures are simply twelve times the monthly ones, so they cover twelve times the days you entered per month — at the default 30 days that is a 360-day year, about 1.4% short of 365 days. Enter 30.4 days per month if you want the yearly total to track a full calendar year.
- Motor and heating appliances rarely draw their rated wattage continuously — a fridge or thermostat-controlled heater cycles on and off, so its real average draw is well below the plate rating.
How this is calculated
- Power in kilowatts
- 1.000 kW
- Hours per day
- 4.0 h
- kWh per day = kW × hours
- 4.000 kWh
- Days used per month
- 30 days
- kWh per month
- 120.00 kWh
- Rate
- $0.170
- Cost per month = kWh × rate
- $20.40
- Cost per year = month × 12
- $244.80
Months
Compare scenarios
See how one change moves the result
- CurrentYour inputs as they stand$20.40Current
- Appliance powerW 1,250$25.50
- Hours used per dayh 5$25.50
- Days used per monthdays 31$21.08
Frequently asked questions
How do I find an appliance’s wattage?
Look for the rating plate — usually a sticker on the back, base, or inside the door — or the specifications page of the manual. It will list watts (W) or amps and volts, and watts equals amps multiplied by volts. A plug-in energy monitor gives you the real figure instead of the rated maximum.
What is a kilowatt-hour?
A kilowatt-hour is the energy used by a 1000-watt appliance running for one hour, and it is the unit your utility bills you in. A 2000-watt kettle uses 1 kWh in half an hour; a 10-watt LED bulb takes 100 hours to use the same amount.
What rate per kWh should I enter?
The most honest number is your bill total divided by the kilowatt-hours billed, because that folds in standing charges, delivery fees, and taxes. Using only the headline energy rate will understate what an extra unit of consumption actually costs you.
Why is my real bill higher than this estimate?
Bills include a fixed daily standing charge you pay regardless of usage, and they cover every appliance in the home rather than the one you entered. Seasonal heating and cooling, plus always-on standby loads across dozens of devices, usually account for the rest of the gap.
Does standby power matter?
It adds up. A device idling at 3 watts costs little on its own, but a household with twenty such devices carries roughly 525 kWh of phantom load a year, which is a real line on the bill for electricity that does no work at all.