The Kia Optima tail light utilizes 2357, 1157, and P21/5W bulb sizes depending on the specific version of the vehicle. Available data covers a range from 2001 through 2019.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 12961 is a Philips miniature wedge bulb in the T10 form factor, using a W2.1x9.5d base and rated at 12V, 5W. In the Kia Optima, it serves the inner tail light position on 2017-2020 models equipped with either Single Projector-Type or Halogen Capsule headlamps.
The P21/5W follows the ECE standard used in Europe and worldwide markets. It is a dual-filament signalling bulb with a BAY15d bayonet base, rated at 12V with filaments at 21W and 5W. It occupies the outer tail light position on the Kia Optima for 2017-2020 under specific headlamp configurations.
The 1157 is an ANSI-standard dual-filament bulb sharing the BAY15d bayonet base with the P21/5W and carrying identical voltage and wattage ratings of 12V, 21W/5W. Despite these matching electrical characteristics, the 1157 and P21/5W are separate standards and are not listed interchangeably within these specifications.
The 2357 is also an ANSI-standard dual-filament bulb with a BAY15d bayonet base, but it operates at higher wattages of 26.9W and 8W compared to the 1157. This makes it a brighter output variant rather than a direct substitute for the 1157.
The outer tail light position on the Kia Optima uses the 2357 bulb for model years 2003-2010, representing a higher-output fitment relative to the 1157 used in later years.
The outer tail light on 2011-2013 Kia Optima models with Halogen Capsule headlamps uses the 1157 bulb, while the 2017-2018 outer tail light fitment of 1157 applies specifically to vehicles without LED tail lights, indicating that trim-level or package differences affect bulb selection within the same model year.
The BAY15d bayonet base is shared across the P21/5W, 1157, and 2357 bulb types present in these specifications. While the base type is physically common, the differing wattage ratings and regulatory standards mean substitution across these types is not supported by the listed fitment data.
The outer tail light position on the 2019 Kia Optima lists both the P21/5W and the 1157 as applicable bulb sizes, with the P21/5W tied to the Halogen Capsule headlamp configuration and the 1157 carrying no stated condition, reflecting that multiple valid fitments exist for that year depending on vehicle specification.
The inner tail light position consistently uses the 12961 across all four listed model years (2017-2020), with no variation by trim or headlamp type beyond the stated headlamp configuration qualifier, making it the most uniform fitment across the specifications provided.
The outer tail light specifications span model years 2001-2020 for the Kia Optima, covering three distinct bulb types across that range, with the 2357 appearing exclusively in the 2003-2010 period and representing the only fitment in these specifications rated above the 21W/5W threshold common to the 1157 and P21/5W.