Lexus RX350L front turn signal uses 7444NA bulb size while rear turn signal requires 7440NA bulb size. The replacement bulb chart covers 2018 to 2021 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The two bulb types specified for the Lexus RX350L are the 7444NA and the 7440NA, both of which conform to ANSI standards recognized in the United States and Canada.
Both the 7444NA and 7440NA belong to the T20 wedge family, meaning they share the same physical base style, though their filament configurations differ from one another.
The 7444NA is a dual-filament bulb rated at 12V with a 21W/5W output, where the higher wattage filament serves the primary turn signal function and the lower wattage filament serves a secondary role such as a parking or position light.
The 7440NA is a single-filament bulb rated at 12V and 21W, dedicated solely to the turn signal function without a secondary lighting circuit.
Both bulb types use natural amber glass rather than a clear envelope with a coated or colored base, which produces the amber output required for turn signal applications.
The front turn signal positions on the RX350L call for the 7444NA across the 2018-2021 model years, reflecting a dual-filament requirement at that location.
The rear turn signal positions call for the 7440NA across the same 2018-2021 span, indicating a single-filament circuit at the rear.
Although the 7444NA and 7440NA share the T20 wedge base, the difference in filament count makes them non-interchangeable; installing a single-filament 7440NA in a socket designed for the dual-filament 7444NA would leave one circuit without a functioning light source.