Science · free · no sign-up
Electricity Calculator
Estimate energy use, running cost and electric charge for an appliance from its power rating and how long it runs.
Electricity Calculator
Electrical energy, cost, charge, and capacitance calculations
E = P × t | Q = I × t | Cost = kWh × rate
W
hours
Result
—
Stat 1
—
Stat 2
—
Stat 3
—
Step-by-Step
—
About the Electricity Calculator
Estimate energy use, running cost and electric charge for an appliance from its power rating and how long it runs.
How to use the Electricity Calculator
- Choose Electric Energy, Energy Cost or Electric Charge.
- Enter the Power (P) in watts, Time or Usage per Day and the Electricity Rate per kWh (or the Current (I) for charge).
- Press Calculate.
Formula and method
Energy (kWh) = Power (kW) × Time (h), Cost = Energy × Rate and Charge (C) = Current (A) × Time (s).
Worked example
A 1,500 W heater running 3 hours uses 4.5 kWh. At $0.12 per kWh that costs $0.54.
Tips
- Standby power adds up. Switch off devices you are not using.
- Look for the wattage on the appliance label.
Frequently asked questions
How do I find my electricity rate?
It is printed on your bill, usually in cents or pence per kWh.