Audi 100 Series License Plate Bulb Size

The Audi 100 Series license plate light uses 97 and 1816 bulb sizes for the specific lighting components. Data for the provided bulb specifications covers the range from 1969 to 1977.

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
1973-1977	97
1969-1972	1816

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	97
ANSI standard (US & Canada). Miniature wedge bulb (T3.25). 12V, 4W.	1816

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Additional Notes

The Audi 100 Series license plate bulb specifications cover model years 1969-1977, with two distinct bulb types used across that span.
Model years 1973-1977 use the type 97 bulb, while model years 1969-1972 use the type 1816 bulb. These two types are not interchangeable.
Both the 97 and 1816 are ANSI-standardized bulbs recognized in the United States and Canada.
The type 97 bulb operates at 12 volts and 13 watts. It uses a BA15s bayonet base, which is a single-contact bayonet fitting commonly found in automotive applications.
The type 97 is a single-filament bulb and is classified as a variant of the 1156 bulb family, meaning it shares the same BA15s base but differs in wattage or other electrical characteristics from the standard 1156.
The type 1816 bulb operates at 12 volts and 4 watts, making it significantly lower in wattage than the type 97. It uses a miniature wedge base rather than a bayonet fitting.
The 1816 is a T3.25 bulb, a designation that refers to its tubular shape with a width of 3.25 eighths of an inch, which is a standard sizing convention for miniature automotive bulbs.
The base types of the two bulbs are mechanically incompatible. The BA15s bayonet base of the type 97 and the wedge base of the type 1816 require different sockets.