Kia Niro Back Up Light Bulb Size

The Kia Niro back up light bulb uses a P21W size, also designated as 921. The replacement chart covers vehicle production spanning 2017 to 2024.

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
2023-2024	P21W
2017-2022	921

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

The Kia Niro backup light specifications cover the 2017-2024 model years, with two distinct bulb types used across that span.
The 921 bulb is the more frequently specified type, appearing across the 2017-2022 model years, while the P21W is specified for 2023-2024.
The 921 is an ANSI-standard wedge bulb in the T15 form factor, rated at 12V and 16W.
The P21W follows the ECE standard used in Europe and worldwide markets, featuring a BA15s bayonet base and rated at 12V and 21W.
The BA15s base on the P21W is a single-contact bayonet fitting, which is physically and electrically incompatible with the wedge socket used by the 921.
The 921 and P21W also differ in wattage, with the P21W drawing 21W compared to the 921's 16W, meaning the two types are not interchangeable even with an adapter.
The shift from the 921 to the P21W between the 2022 and 2023 Kia Niro reflects a change in the bulb standard used, which corresponds to a generational redesign of the vehicle.
Both bulb types are single-filament designs, consistent with their use in a dedicated backup light function rather than a combined stop/tail application.