Choosing the right headlight size for your motorcycle can be confusing. With different manufacturers using different housing dimensions, mounts, bucket depths, and connector types, it’s easy to wonder: “What size headlight fits my bike?”
This comprehensive guide explains exactly how to determine the correct headlight size for your motorcycle—whether you ride a Harley-Davidson, Indian, Honda, Yamaha, Triumph, BMW, or any custom or café-style bike.
We break down all major headlight sizes, show how to measure your current setup, explain how to identify your bike’s fitment, and provide a detailed model-by-model fitment chart. You’ll also learn what tools you need, which adapters may be required, and how LED upgrades affect sizing.
Why Motorcycle Headlight Size Matters
A motorcycle headlight is more than just a light—it’s a critical safety component. Choosing the wrong size can lead to serious visibility issues. The correct size ensures:
- Proper beam alignment so you can see the road clearly
- Exact fitment inside the motorcycle’s headlight housing
- No vibration or shaking due to loose fitment
- Correct wiring compatibility with the bike’s harness
- Optimal brightness and legal DOT projections
This is especially important when upgrading from halogen to LED, since LEDs are heavier, brighter, and more precise.
Common Motorcycle Headlight Sizes
While there are dozens of specialty headlight sizes, most motorcycles use one of a few standard sizes. These sizes refer to the diameter of the headlight lens across the front.
Most Common Motorcycle Headlight Sizes:
- 5.75-inch (5 3/4") – used on many Harley Sportster, Dyna, and custom bikes
- 7-inch – used on Harley Road King, Street Glide, Electra Glide, many BMWs, and custom café racers
- 4.5-inch passing lamps – auxiliary lights used on Harley touring models
- Dual 5.75-inch headlights – used on pre-2015 Harley Road Glides
- Single molded assemblies – used on 2015+ Road Glide, BMW touring, and modern bikes
Some modern motorcycles use proprietary LED headlight modules that don’t follow standard inch-based sizing and require model-specific replacements.
How to Determine What Size Headlight Fits Your Bike
If you’re unsure what size headlight your motorcycle uses, here is a step-by-step process.
Step 1: Measure Your Current Headlight
Use a ruler or tape measure and measure across the widest point of the headlight lens.
Measurements to take:
- Diameter (the most important measurement)
- Depth of the headlight bucket
- Mounting point width between the ears or nacelle
- Connector type (H4, H13, or proprietary)
The diameter will tell you the headlight size. Bucket depth is important if you’re upgrading to LED, since LED housings are deeper.
Step 2: Identify Your Bike’s Make, Model, and Year
Headlight size depends heavily on your motorcycle’s exact year and model.
For example:
- A 2012 Harley Sportster uses a 5.75-inch headlight.
- A 2020 Harley Road King uses a 7-inch headlight.
- A 2010 Road Glide uses dual 5.75-inch headlights.
- A 2023 Road Glide uses a one-piece proprietary LED assembly.
Even within the same model family, Harley changed headlight fitment across model-year generations.
Step 3: Check Your Mounting Style
Motorcycle headlights attach to the bike in one of three common ways:
1. Fork-Mounted (Side Mount)
These use headlight brackets or “ears” that attach to the front forks.
2. Nacelle-Mounted
Found on Softail Deluxe, Heritage, Road King, and other classic models.
3. Fairing-Mounted
Like Street Glide, Road Glide, Indian Chieftain, and BMW touring models.
Your mount style affects not only size but also bracket compatibility and installation requirements.
Step 4: Determine Your Connector Type
Most motorcycles use one of the following:
- H4 (3-prong) – the most common for LED upgrades
- H13 – used on certain touring bikes
- Proprietary connectors – used on newer motorcycles with stock LED units
If your bike uses a proprietary wiring harness, an adapter may be required.
Motorcycle Headlight Fitment: By Brand
Below are the most accurate headlight size recommendations for major brands.
Harley-Davidson Headlight Size Guide
Harley-Davidson has standardized headlight size across most models.
5.75-inch Harley Models
- Sportster (all years)
- Dyna Street Bob
- Dyna Super Glide
- Dyna Low Rider (pre-M8)
- Softail Standard
- Breakout (certain years)
- Night Train
7-inch Harley Models
- Road King
- Street Glide
- Electra Glide
- Ultra Limited
- Softail Heritage
- Deluxe (certain years)
Harley Road Glide Models
- 1998–2013: Dual 5.75" headlights
- 2014: Dual 5.75" headlights (updated fairing)
- 2015+ Road Glide: One-piece proprietary LED assembly
Harley Passing Lamps
Most models with passing lamps use 4.5-inch auxiliary headlights.
Indian Motorcycle Headlight Size Guide
Indian Bikes That Use 7-Inch Headlights:
- Indian Chief
- Chief Dark Horse
- Vintage
- Classic
- Springfield
Proprietary Headlight Models:
- Indian Chieftain
- Roadmaster
- Challenger
These require bike-specific LED assemblies.
Honda, Yamaha, Kawasaki, Suzuki Headlight Sizing
Japanese motorcycles often use metric headlight sizing, but many still use standard LED sizes.
Common Japanese Motorcycle Fits:
- 7-inch – classic bikes, café racers, older standards
- 5.75-inch – sport standards and cruisers
- Proprietary – modern sport bikes with molded LED units
BMW, Triumph, Ducati, & European Bike Headlight Sizes
- BMW GS series – proprietary LED assemblies
- BMW R nineT – 7-inch headlights
- Triumph Bonneville – 7-inch
- Triumph Thruxton – 7-inch
- Ducati Scrambler – proprietary premium LED module
How LED Headlight Upgrades Affect Sizing
LED headlights are larger and heavier than halogen units, so installers must consider:
- Housing depth: LED units extend deeper into the bucket
- Heat sink clearance: LED cooling systems require space
- Connector clearance: wiring harnesses need room
On some bikes, you may need:
- A retaining ring
- A bucket extender
- A mounting bracket
Motorcycle Headlight Fitment Table (Universal)
| Bike Type | Headlight Size | Notes |
|---|---|---|
| Harley Sportster | 5.75" | Plug-and-play LED upgrade |
| Harley Road King | 7" | Some years need bracket |
| Harley Road Glide (1998–2013) | Dual 5.75" | LED dual kits recommended |
| Harley Road Glide (2015+) | Proprietary | Requires full LED assembly |
| Indian Chief | 7" | Standard fit |
| Indian Chieftain | Proprietary | Model-specific only |
| Triumph Bonneville | 7" | Direct-fit LED |
| Honda Shadow | 7" | Varies by year |
| Most café racers | 7" | Most universal headlights fit |
Frequently Asked Questions
How do I know what size headlight fits my motorcycle?
Measure the diameter of your existing headlight lens. Most motorcycles use either a 5.75-inch or 7-inch headlight.
Can I put a different size headlight on my bike?
Yes, but you may need brackets, mounts, or a new housing.
Do all Harley-Davidson bikes use the same headlight size?
No. Sportsters and Dynas use 5.75-inch; touring models use 7-inch; Road Glides use dual or proprietary sizes.
What size is a café racer headlight?
Most café racers and custom builds use 7-inch headlights.
Do LED headlights have different sizes than halogen?
The diameter is the same, but LED units may be deeper and require extra clearance.
How do I find my headlight connector type?
Most motorcycles use H4 or H13 connectors; newer models may have proprietary connectors.
Final Thoughts: Choosing the Right Headlight Size
Finding the correct headlight size for your motorcycle is essential for safety, visibility, and perfect fitment. Whether you ride a Harley, Indian, BMW, Triumph, Honda, Yamaha, or a custom build, choosing the right size ensures optimal illumination and clean installation.
If you want the easiest, safest upgrade possible, LED headlights offer the best performance, longest lifespan, and highest visibility of any lighting option. Once you know your bike’s correct headlight size and mount type, upgrading is simple—and the improvement in nighttime visibility is dramatic.
