Running Watts Calculator

Calculate the running power requirements for electrical devices and appliances

Input Parameters

Standard household voltage (e.g., 120V in North America, 230V in Europe)

Operating current of the device in amperes

Motor or device efficiency (typically 80-95% for household appliances)

Calculation Results

Calculation Formula

Running Watts = (Voltage × Current) × (100 ÷ Efficiency)

Where:
Running Watts - The power consumed when the device is running
Voltage - Electrical system voltage in volts (V)
Current - Operating current in amperes (A)
Efficiency - Device efficiency as a percentage

Running Watts

0.00 W

Running Amps

0.00 A

Power Factor (Optional)

1.00 (Assumed for standard household appliances)

Running Watts Calculator Calculator Usage Guide

Learn how to use the Running Watts Calculator and understand power consumption basics

How to Use This Calculator

  1. Enter the voltage of your electrical system (standard is 120V in North America or 230V in Europe)
  2. Enter the operating current of the device you're calculating for (this can usually be found on the device's label)
  3. Set the efficiency of the device (typically 80-95% for household appliances)
  4. Click the "Calculate" button to determine the running watts

Understanding Running Watts

Running watts represent the amount of power a device consumes while it's operating. This is different from starting watts, which is the power needed to start a motor (like a refrigerator or air conditioner), which is typically higher than running watts.

Why This Matters

Running watts are important for:

  • sizing inverter systems for continuous power needs
  • selecting appropriate power sources for camping or off-grid applications
  • understanding energy consumption for appliance sizing in portable power systems

Example Application

For example, if you have a 120V device that draws 5A of current with 85% efficiency:

Running Watts = (120V × 5A) × (100 ÷ 85) = 706W

This means you need a power source that can continuously supply at least 706W to safely run this device.