Lexus IS300 Map Light Bulb Size

The Lexus IS300 Map Light requires bulb size 12961 or 57 depending on the specific application. Data for the bulb sizes covers the range from 2001 to 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
2017-2019	12961 (Front and Rear)
2016	12961
2001	57

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961
ANSI standard (US & Canada). Single-filament bulb with BA9s base. 12V, 1W.	57

Other Locations

Additional Notes

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 wedge base design means the bulb is held in place by friction against the socket walls rather than by a locking bayonet or screw mechanism.
The bulb size 57 follows the ANSI standard used in the United States and Canada, featuring a BA9s base with a single filament, rated at 12 volts and 1 watt.
The BA9s base on the size 57 bulb is a single-pin bayonet type, which is physically incompatible with the W2.1x9.5d wedge socket used by the 12961, making the two bulbs non-interchangeable.
The 2001 Lexus IS300 uses the size 57 bulb for its map light, while model years 2016-2021 use the 12961, reflecting a difference in socket type across generations.
For the 2017-2019 IS300, the specifications note separate front and rear map light positions, both requiring the 12961 bulb.
The 2021 and 2016 model year entries do not carry a front and rear positional distinction in the specifications, listing only a single 12961 fitment.
At 5 watts, the 12961 draws five times the wattage of the 1-watt size 57 bulb, a difference relevant when considering socket and circuit load tolerances during any replacement.