BMW i3 Dome Light Bulb Size

Additional Notes

• The BMW i3 uses the 12961 bulb for its dome light across the full 2014-2021 model year range covered by these specifications.
• The 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12 volts and 5 watts.
• The T10 designation refers to the bulb's tubular form factor, with the number indicating a width of roughly 10/32 of an inch, a standard sizing convention in miniature automotive bulbs.
• The W2.1x9.5d base type is a wedge-style base in which the glass envelope itself acts as the retention mechanism, requiring no separate metal shell or bayonet pins for fitment.
• At 5 watts, the 12961 falls within the low-wattage range typical of interior courtesy and dome lighting applications, where heat output and current draw are kept minimal.
• The uninterrupted use of the same bulb specification across all eight model years indicates a consistent dome light socket design throughout the i3's production span in these records.
• T10 wedge bulbs share a widely used base standard, though voltage and wattage ratings must match the original specification, as physically interchangeable bulbs with different ratings can cause electrical or thermal issues.