Audi RS3 Tail Light Bulb Size

The Audi RS3 tail light utilizes bulb size 12961 and bulb size P21W for the lighting components. Data for the specified bulbs covers the range from 2023 to 2024.

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
2024	12961
2023	P21W

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The 2024 Audi RS3 tail light uses the 12961, a Philips part number designation for a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W.
The 2023 Audi RS3 tail light uses the P21W, an ECE-standard single-filament signalling bulb with a BA15s bayonet base, rated at 12V and 21W.
The T10 wedge base (W2.1x9.5d) and the BA15s bayonet base are physically incompatible mounting types, meaning bulbs from the 2024 and 2023 specifications are not interchangeable between model years.
The wattage difference between the two specifications is substantial: the P21W draws 21W compared to the 5W of the 12961, reflecting a significant difference in power consumption and light output between the two model years.
The P21W designation follows ECE (Economic Commission for Europe) naming conventions, which are used in international and European automotive lighting standards, while the 12961 designation follows Philips' proprietary part numbering system.
The BA15s base of the P21W is a single-contact bayonet fitting, where the "s" denotes a single contact pin, distinguishing it from dual-contact bayonet variants that are used in dual-filament applications.