Electricity Cost Calculator
Estimate the running cost of an appliance from its wattage and usage.
Curious what a device costs to run? Enter its power in watts, how many hours a day you use it and your electricity price per kWh, and this tool estimates the daily, monthly and yearly cost — great for spotting energy-hungry appliances.
Formula / method
Examples
0.075 / day
0.80 / day
From watts to money
Electricity is billed by the kilowatt-hour (kWh), the energy used by a 1000-watt device running for one hour. The tool computes energy as watts multiplied by hours, divided by 1000, then multiplies by your price per kWh. A 1500 W heater running 3 hours uses 4.5 kWh; at a price of 0.30 per kWh that is 1.35. Longer runtimes and higher wattages scale the cost linearly.
Reading the numbers realistically
The wattage printed on an appliance is usually its maximum draw, and many devices do not run flat out. A fridge cycles its compressor on and off, so it does not consume its rated wattage 24 hours a day, and a heater with a thermostat idles once the room is warm. Standby power from devices left plugged in also quietly accumulates. Treat the result as a solid estimate, and use metered readings for precision. To explore the underlying energy in joules or BTU, see our Energy Converter.
Where it's used
- Estimating what a space heater or air conditioner adds to the bill
- Comparing the running cost of an old appliance against a newer one
- Budgeting for always-on devices like a fridge, router or aquarium pump
- Deciding whether standby 'vampire' devices are worth unplugging
- Costing a long gaming, PC or EV-charging session
Real-world examples
- A 1500 W heater run 3 hours a day uses 4.5 kWh; at $0.30 per kWh that is $1.35 a day, about $40 a month
- A 100 W device on 5 hours a day at $0.15 per kWh costs about $0.075 a day
- A 2000 W load for 2 hours a day at $0.20 per kWh is $0.80 a day
Did you know?
The watt is named after Scottish engineer James Watt, whose improved steam engine helped power the Industrial Revolution; the kilowatt-hour on your bill is simply 1000 watts running for one hour.
FAQ
Where do I find an appliance’s wattage?
Check the label, manual or power supply — it’s usually given in watts (W). Your electricity price per kWh is on your utility bill.