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 Type	Shop
2021	12961	Check Price
2014-2018	12961	Check Price

Bulb Specifications

Description	Type	Shop
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961	Check Price

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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.