18W

18W denotes a power rating of 18 watts, the rate at which energy is transferred or consumed. The watt (W) is defined as one joule per second, so an 18W device converts or draws energy at 18 joules each second under its operating conditions. The term is widely used in labeling electronic equipment to indicate maximum continuous output or consumption.

In consumer electronics, 18W is a common specification for compact fast chargers and related power supplies. Many 18W adapters use USB-C Power Delivery or similar fast-charging protocols and negotiate a suitable voltage and current with the device. Typical profiles may include around 9V at 2A or other combinations that yield approximately 18W; the exact values depend on the charger, the cable, and the device’s charging circuitry. The same 18W rating can also appear on LED lighting or other components to indicate their power draw.

Usage and efficiency: while an 18W charger can deliver up to 18 watts under favorable conditions, actual power delivery can vary based on cable quality, connector type, and device behavior. Efficiency losses during conversion to the device’s operating voltage mean that some power is dissipated as heat in both the charger and the device.

Applications: devices commonly labeled with 18W include smartphones, tablets, small USB-C power banks, and certain LED fixtures. The 18W figure is often contrasted with higher-wattage fast-charging options that deliver more power for faster charging or operation.

See also: watt, power, USB Power Delivery, fast charging, LED lighting.