Ram 1500 Classic Dome Light Bulb Size

The Ram 1500 Classic dome light requires a bulb size of 578 for proper installation and function within the interior lighting system. Data for the specified component covers the range from 2019 through 2023.

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	578
2021	578
2019	578

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V, 12W.	578

Other Locations

Additional Notes

The 578 bulb is the dome light specification for the Ram 1500 Classic across the 2019-2023 model years covered in these specifications.
The 578 is a festoon-type bulb, meaning it is cylindrical in form and makes electrical contact through metal caps at each end rather than through a base socket.
At 41mm in length, the 578 fits into festoon holders that grip the end caps, a mounting style common in interior dome and map light applications.
The 578 operates at 12 volts and 12 watts, which is consistent with standard automotive interior lighting powered directly from a vehicle's 12V electrical system.
The 578 carries ANSI designation, indicating it meets a standardized specification recognized in both the United States and Canada.
Festoon bulbs of the same voltage and wattage are produced in multiple lengths, so the 41mm length of the 578 is a critical fitment detail, as a bulb of a different length will not seat correctly in the holder even if the end-cap contact style matches.