Headlights are rated by the Insurance Institute for Highway Safety. Since 2016, the IIHS has tested and rated original equipment manufacturer headlight systems across vehicle makes and models.
These ratings make it easier to select a vehicle with good headlights and identify the best auto parts for replacing headlight bulbs and assemblies. Find out more about headlight ratings and how to change a headlight to maximize visibility in low-light conditions.
Learn the Difference Between Headlight Types
Halogen headlights are incandescent and have been the industry standard for years. These bulbs are not as bright and do not last as long as light-emitting diode, Xenon or high-intensity discharge lights. Halogen lights are the lowest in cost, but upgrading to HID or LED lights can be affordable.
The IIHS factors brightness and glare into headlight ratings. In general, Xenon or HID lights give off more glare than halogen or LED headlights. LED lights are the longest lasting option and are more customizable than halogen or HID.
IIHS ratings are based on the reach of headlights on a vehicle driving straight and around curves. A track is equipped with sensors to measure exactly how far light extends from the vehicle with an intensity of at least 5 lux, a unit of illuminance.
Five approaches are used in testing: straightaway gradual left and right curves with an 800-foot radius and sharp left and right curves with a 500-foot radius. Visibility readings are taken from the edges of the roadway at 10 inches above ground level.
Other factors in headlight design that affect IIHS ratings include curve-adaptive headlights that increase visibility by adjusting based on steering and high-beam assist that automatically switches beams based on the proximity of other vehicles.
Many headlights emit less light on the left side of straight roads to reduce glare to oncoming vehicles. Glare readings are taken from seven inches above the ground.
After three valid tests, the IIHS rates the performance of a vehicle headlight system factoring in any demerits. An average of visibility distances, glare exposure curves and peak glare values determine the overall rating of the system.
The range of demerits determines the rating, with 0 to 10 demerits earning a good rating, 11 to 20 demerits being rated as acceptable, 21 to 30 merits being classified as marginal and more than 30 demerits resulting in a poor rating
Knowing When To Replace Your Headlights
Headlight ratings only apply to new OEM systems in vehicles. Over time, bulbs may dim or wear out and pose visibility and safety hazards.
A vehicle may also sustain damage to headlight assemblies that reduces or eliminates illumination. It is important to replace burnt out bulbs, clouded or broken assemblies and faulty fuses to maintain this safety system.
Headlights are federally regulated, but these standards only establish minimum standards for headlight performance. IIHS ratings go beyond baseline standards to account for the quality of light emitted by headlights. The best type of headlights for a vehicle depend on the design and assembly of the headlight system and road conditions where you drive.