MR16

MR16 is a size-classification for a family of small reflector lamps. The name derives from Multifaceted Reflector and the 16, which historically denotes the reflector’s diameter in one-eighth inch units (about 50 mm). Most MR16 lamps use a two-pin base, with GU5.3 being the common low-voltage variant, and are designed for directional lighting in fixtures such as track lighting, recessed downlights, and display lighting.

There are two main base and voltage configurations. Low-voltage MR16 lamps use a GU5.3 bi-pin base and typically operate from around 12 volts with a dedicated transformer or driver. Mains-voltage MR16 lamps use a GU10 base and run directly on line voltage, often in similar form factors. In addition to these, other bases exist but are far less common in standard installations. The choice of base affects installation, transformer or driver requirements, and dimming capability.

Halogen MR16 lamps have wattages commonly in the 20–50 watt range and are valued for bright, directional light with high color rendering. They are widely used for accent lighting, architectural highlights, and display illumination. Heat output is relatively high for halogens, and lamp life is shorter than many modern alternatives.

LED MR16 lamps reproduce the MR16 form factor and bases (including GU5.3 and GU10) while using only a few watts (often 3–9 W) and offering longer lifetimes (often 15,000–40,000 hours). They produce less heat and can be more energy-efficient, but performance depends on the driver, beam angle, and color temperature. Compatibility with existing transformers, dimmers, and fixture housings should be verified when replacing halogen MR16 lamps with LEDs.