BMW i3 Stepwell Bulb Size

The BMW i3 stepwell light requires a bulb with the specific 12961 size for proper installation and function within the interior lighting system. Data for the lighting components covers the period from 2014 through 2021.

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
2021	12961
2014-2018	12961

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961

Other Locations

Additional Notes

The BMW i3 uses the 12961 bulb for its stepwell position across the 2014-2021 model years.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, operating at 12 volts and rated at 5 watts.
The T10 designation refers to a tubular bulb with a width of 10 thirty-seconds of an inch, a common sizing standard in automotive interior and courtesy lighting applications.
The base type is W2.1x9.5d, a wedge-style base in which the glass envelope itself acts as the retention mechanism rather than a separate metal base, fitting into a corresponding wedge socket.
At 5 watts, the 12961 falls within the low-wattage range typical of courtesy and interior accent lighting, where heat output and power draw are kept minimal.
The W2.1x9.5d base specification is a precise fitment detail, and substituting a bulb with a different base type would result in an incompatible socket fit regardless of voltage or wattage similarity.