The Kia Forte brake light utilizes 2357 and P21/5W bulb sizes for the rear lighting system. Available data for the specified vehicle covers the range from 2010 through 2024.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 2357 bulb is the most frequently specified brake bulb across the Kia Forte range, appearing in the brake light position for model years 2010-2013 and 2022-2024, as well as 2014-2018 vehicles equipped with halogen capsule headlamps. It is a dual-filament bulb operating at 12V with a high-filament draw of 26.9W and a low-filament draw of 8W, fitted with a BAY15d bayonet base under the ANSI standard used in the United States and Canada.
The 2357 is described as a brighter variant of the 1157 bulb. Both share the BAY15d bayonet base, which means the 1157 is physically interchangeable with the 2357, though the two differ in wattage output. Substituting one for the other may affect light intensity.
The 2021 Kia Forte brake light position uses the P21/5W rather than the 2357. Although both bulbs share the BAY15d bayonet base, the P21/5W follows the ECE standard and operates at 21W/5W, making it a different specification from the ANSI-rated 2357. The shared base type does not make them direct equivalents for this application.
The Center High Mount Stop Light transitioned from the 921 wedge bulb to the P21W between the 2013 and 2014 model years. The 921 is a T15 wedge type with no base pins, while the P21W uses a BA15s single-pin bayonet base, meaning the two are not physically interchangeable despite both operating at 12V.
The P21W is a single-filament ECE-standard bulb rated at 12V and 21W, fitted with a BA15s bayonet base. Its single-filament design distinguishes it from the dual-filament P21/5W, and the differing base types (BA15s versus BAY15d) prevent cross-substitution between the two.
The 921 bulb, specified for the Center High Mount Stop Light on 2010-2013 models, is a T15 wedge type rated at 12V and 16W under the ANSI standard. Its wedge construction requires no locking mechanism, relying instead on socket tension for retention.
The 12961 is a Philips part number designating a miniature T10 wedge bulb with a W2.1x9.5d base, rated at 12V and 5W. It is specified for the Inner Brake position on the 2021 and 2023 Forte. The T10 wedge format and low wattage rating set it apart from all other bulb types in these specifications, and it is not interchangeable with any of them.
The 2014-2018 brake light entries carry the qualifier "With Halogen Capsule Headlamps," indicating that the 2357 fitment for those years is conditional on headlamp type. No brake bulb specification is listed for those years without that condition.