Festoon Base LED Bulbs: How to Get the Right Size

If you’ve ever needed to replace any 12-volt bulb found in automotive interior lighting or marine lighting, you have likely seen a festoon base bulb. Festoon bulbs are specialty miniature bulbs with a distinctive cylindrical shape with the light-emitting element between two contacts at opposite ends. The contacts or end caps can be cone-shaped, flat (fuse style), or dimpled, depending on the type of socket it is meant to fit.

LED festoon bulbs are typically measured in millimeters (mm) and come in various sizes, depending on the intended application and the specific product. Some standard lengths for LED festoon bulbs include 38mm, 42mm, and 48mm.

Manufacturers use different model numbers for the festoon 12-volt light bulb. Some examples include the 3175 LED bulb, 6418 LED bulb, 6411 LED bulb, 6418 LED bulb, and 3175 LED bulb.

The compatible base number, lamp size, and socket type are often included. SV8.5, and SV7-8 are standard festoon bases, and 3175 and 3022 (sometimes shown as DE3175 and DE3022) are common socket types in automotive and marine applications.

Ensuring the correct size and wattage for the intended application is essential when replacing a festoon light bulb. When replacing automotive bulbs, you can use our vehicle bulb finder tool to locate compatible replacements based on the year, make, and model.

Be sure to consult the manufacturer's specifications, measure the bulb and socket length, and check for cross-compatibility in the lamp specification. Consult with one of our qualified lighting professionals if you have any questions or concerns.