Milliwatt (mW)

The milliwatt is a unit of power equal to one-thousandth of a watt:

1 mW = 0.001 W

It is commonly used to express low power levels in electrical and electronic systems, particularly where precision and energy efficiency are critical.

Power Calculation

Power in milliwatts can be calculated using:

P (mW) = V (V) × I (mA)

where:

• P: Power in milliwatts

• V: Voltage in volts

• I: Current in milliamps

This form is especially useful when working with small devices powered by batteries or low-voltage sources.

Practical Examples

• A laser pointer typically operates at 5 mW

• A smartphone charger delivers around 5,000 mW (5 W)

• A Bluetooth transmitter may operate at 1–100 mW, depending on power class and range

Applications

• Telecommunications: Measuring output power of RF devices (e.g., Wi-Fi, Bluetooth) to ensure regulatory compliance

• Medical devices: Monitoring low power usage in portable diagnostic tools

• Consumer electronics: Battery management and energy efficiency optimization

• Optical systems: Power ratings of laser diodes and photodetectors