Buick Regal Sportback Back Up Light Bulb Size

The Buick Regal Sportback back up light uses a bulb size of 921 for the rear lighting assembly. Data for the bulb size covers the range from 2018 to 2020.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2018-2020	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

Other Locations

Additional Notes

The 921 bulb is the specified back up light bulb for the Buick Regal Sportback across the 2018-2020 model years.
The 921 is a wedge-type bulb, classified under the T15 form factor, which refers to its tubular shape with a width of 15/8 of an inch.
The 921 operates at 12 volts and draws 16 watts, consistent with standard automotive low-voltage electrical systems.
The 921 carries ANSI standardization, meaning its physical and electrical characteristics conform to a defined industry specification recognized in both the United States and Canada.
The wedge base design of the 921 means it is held in its socket by the tension of the base itself rather than by a separate locking mechanism, which is a common trait in reverse and interior lighting applications.
Because the 921 is an ANSI-standardized bulb, other bulbs sharing the same T15 wedge base and 12V/16W rating are generally considered interchangeable, provided they meet the same dimensional and electrical parameters.