Light Bulb Sizes for Cars and Trucks: Your Complete Off-Road and On-Road Guide

April 02 2025

Light Bulb Sizes for Cars and Trucks: Your Complete Off-Road and On-Road Guide

When it comes to maintaining or upgrading your vehicle—especially if you're driving off-road—one of the most overlooked components is lighting. Whether you’re navigating a mountain trail or driving through fog on a dark back road, choosing the right light bulb size can make all the difference between visibility and vulnerability.

This complete guide breaks down the most common light bulb sizes for cars and off-road trucks, what each one is used for, and how to find the perfect fit for your vehicle.

🚗 Why Light Bulb Size Matters in Automotive & Off-Road Applications

Each vehicle—whether a commuter sedan or lifted 4x4—uses specific bulbs designed to fit in proprietary housings. Using the wrong size bulb can lead to:

❌ Overheating and electrical failure
❌ Improper beam alignment (blinding oncoming drivers)
❌ Water leaks in off-road sealed housings
❌ Dashboard errors (if not CANbus-compatible)

Upgrading or replacing with the correct bulb size ensures optimal fit, performance, and reliability.

📌 Source: NHTSA.gov

🛠️ Common Light Bulb Sizes for Cars & Off-Road Trucks

🔦 Headlight Bulbs (Low Beam / High Beam / Dual Beam)

Bulb Code	Use	Notes
H11	Low beam / fog light	One of the most common headlight bulbs, also used in fog housings
9005	High beam	Extremely bright; found in many Toyota, Ford, and Chevy trucks
9006	Low beam	Typically paired with 9005 in dual headlight systems
H4 / 9003	Dual beam (hi/lo)	Used in motorcycles and trucks with a single bulb for both functions
H1 / H3	Fog lights / high output beams	Often used in off-road light bars and projectors
H13 / 9008	Dual beam	Found in many Jeeps and trucks with larger headlight housings

💡 Tip: Many trucks and off-road vehicles have projector or reflector housings, which may require different bulb sizes or adapters when upgrading to LED or HID.

📌 Source: PowerBulbs

🌫️ Fog Light Bulb Sizes

Bulb Code	Notes
H11	The most common fog light size; easy to upgrade to LED
H10	Used in many off-road bumper-mounted fog assemblies
9145 / 2504	Found in Ford trucks, SUVs, and some Jeeps
H16	Smaller fog bulb size, often used in imported cars/trucks

🚙 Pro tip for off-roaders: Look for IP67-rated LED fog light kits to prevent water intrusion during mud, rain, or river crossings.

📌 Source: CarID

🔁 Turn Signals, Brake, Tail & Reverse Light Bulb Sizes

Bulb Code	Function	Common Vehicles
7440 / 7443	Tail, turn, reverse	Toyota, Jeep, Ford F-series
3157 / 3057	Tail, brake, reverse	Chevrolet, Dodge Ram, GMC
1157 / 1156	Brake / turn / reverse	Older vehicles and trailers
T15 / W16W	Backup lights	Found in newer trucks and SUVs
921	Reverse lights	Often found in cargo and dome lighting too

💡 Note: Use CANbus-compatible LEDs to avoid “bulb out” warnings or hyper-flashing, especially in modern vehicles with onboard diagnostics.

📌 Source: SuperBrightLEDs

💡 Interior & License Plate Bulb Sizes (Trucks & SUVs)

Bulb Code	Application
194 / T10	Interior dome, map, license plate, side markers
168	Glove box, trunk, footwell
31mm / 36mm / 39mm / 42mm festoon	Dome and cargo lights in trucks and vans
T15	High-output cargo lights (especially in pickup beds)

📌 Source: LightBulbs.com

🔧 How to Find the Correct Bulb Size for Your Vehicle

Here are the most accurate ways to determine the correct size for your car or truck:

Use a Trusted Vehicle Fitment Guide
📘 Download the Performance Headlight Guide PDF – search by year, make, and model for every bulb type in your car or truck.
Check Your Vehicle Owner’s Manual
Look in the maintenance or electrical section for a full bulb chart.
Inspect Existing Bulbs
The bulb code is usually etched onto the glass or base (e.g., H11, 3157, etc.).
Use Online Tools
Websites like BulbSize.com or SuperBrightLEDs Vehicle Finder can confirm compatibility.

💡 Choosing Between Halogen, LED, and HID Bulbs

Type	Pros	Cons	Best For
Halogen	Cheap, easy to replace	Short lifespan, dimmer output	Stock replacements
LED	Long-lasting, bright, energy-efficient	May require adapters, higher upfront cost	Off-road lighting, performance upgrades
HID	Extremely bright, good for high-speed driving	Can cause glare, longer warm-up	Projector headlights, luxury vehicles