About the Wattage Calculator
Power draw from voltage and current, or from energy used over a period.
Also known as: watts calculator, power draw calculator, amps to watts, appliance wattage.
How to use this calculator
- Enter calculate from and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
P = V × I × PF · P = kWh × 1000 ÷ hours
Worked example
Using the values pre-filled in the calculator above:
- Calculate from: Voltage and current
- Voltage = 230 V
- Current = 5 A
- Power factor = 1
the calculator returns:
- Power: 1,150 W
- In kilowatts: 1.15
- In horsepower: 1.5422
- Energy per hour: 1.15 kWh