Curious how much a device is really adding to your electric bill? This calculator turns wattage and usage time into a monthly kWh total and estimated cost.
How to Use This Calculator
Enter the device’s power rating in watts, how many hours per day you use it, how many days per month, and your electricity rate per kWh (check a recent bill), then click Calculate.
Formula
kWh = (Watts ÷ 1000) × Hours per Day × Days per Month. Cost = kWh × Rate per kWh.
Frequently Asked Questions
How do I find my electricity rate?
Check a recent utility bill — it’s usually listed as cents or dollars per kWh, or you can divide your total bill by your total kWh used.
What’s a rough estimate for a space heater’s monthly cost?
A 1500W heater run 3 hours a day for 30 days at $0.15/kWh costs about $20.25/month — try it in the calculator above with your own numbers.
Does this include standby power?
No — this calculates only active-use time. Devices left plugged in on standby draw a small additional amount not included here.