Choose an LED sealed-beam headlamp if your vehicle uses a standard round or rectangular sealed-beam format and you drive at night regularly. It will match the old lamp code, deliver more usable road light, and draw less power. Keep a halogen sealed beam only for a restoration where original appearance and lowest purchase cost come first, or for a vehicle that rarely sees darkness. The single most important rule: match the code on your old lens first, confirm it fits the bucket, wiring, and retaining ring, and check that the lamp carries the required markings and a controlled road beam. Do not choose by size alone, and do not choose by the lumen number on the box.
Quick Answer
If your vehicle uses a standard sealed-beam format and you drive at night more than occasionally, buy an LED headlamp that matches the old lamp code, size, beam function, connector, voltage, and mounting depth. If you are restoring a classic car and want original looks and easy local replacement, stay with a halogen sealed beam. For four-headlight systems, confirm every inner and outer position before ordering. IIHS research shows vehicles with good-rated headlights have 19% fewer nighttime single-vehicle crashes and 23% fewer pedestrian collisions than vehicles with poor-rated headlights, beam performance, not the lumen number, is what actually reduces crash risk.
Start With the Headlight Already on Your Vehicle
Your existing headlight is the starting point, not the vehicle name and model year. Older vehicles may have replacement buckets, altered wiring, different trim packages, or previous lighting conversions. Remove one old lamp only after you have recorded its position and photographed the lens code, rear connector, wires, retaining ring, and the space behind it.
| Your Vehicle or Priority | Best Starting Choice | What You Must Confirm |
|---|---|---|
| Original restoration, limited night driving, lowest purchase cost | Halogen sealed beam | Lamp code, voltage, beam function, and aim |
| Older car, truck, Jeep, motorcycle, or fleet vehicle driven at night | LED sealed-beam headlamp | Size, code, bucket depth, retaining ring, connector, pinout, road beam, and markings |
| Four small rectangular headlights | 4×6 family | Inner and outer positions may have different beam functions and terminals |
| Two larger rectangular headlights | 5×7 / 7×6 family | Look for an H6054-style code, then check depth and wiring |
| Two large round headlights | 7-inch round family | Look for an H6024 or PAR56-style format, then check the bucket and retaining ring |
| Modern molded headlight that follows the body shape | Vehicle-specific bulb or complete assembly | Owner’s manual, OEM part number, bulb designation, trim, and factory lighting package |
If your old headlight has a standard round or rectangular sealed-beam shape, continue with this guide. If it is a molded assembly, use the specified replacement bulb or a vehicle-specific complete assembly instead.
What “Sealed Beam” and “LED” Actually Describe
A traditional sealed-beam headlight combines the lens, reflector, and filament in one indivisible unit. When the filament fails, you replace the whole lamp. Federal rules define a sealed-beam headlamp as an integral optical assembly with “SEALED BEAM” molded into the lens.
LED describes the light source. An LED headlight may also be a complete, sealed, integral lamp. This is why the useful comparison is usually halogen sealed beam vs LED sealed-beam replacement, not sealed beam vs LED.
The distinction matters in the United States. Under FMVSS No. 108, an integral beam headlamp is defined as one optical assembly, and NHTSA evaluates it as a whole unit against photometry and color requirements rather than certifying the light source on its own. Installing an LED light source into a housing designed for a different light source changes the relationship among the emitter, reflector, and lens. That change can produce glare, weak distance lighting, or an irregular cutoff even when the package claims a high lumen output.
A 2006 Texas A&M study quantified how much older sealed-beam designs fall short: comparing sealed beam headlamps to modern headlamps, researchers observed about a 26 percent reduction in illuminance at a distance equal to the stopping sight distance. In other words, a sealed beam simply does not put as much light on the road at the distance where you need to see an obstacle and stop.
Identify Your Current Headlight Before You Shop
Photograph the lens code, rear connector, wires, retaining ring, and the space behind the lamp. If the vehicle uses four headlights, label each photo as driver outer, driver inner, passenger inner, or passenger outer.
Read the Code on the Lens
The molded or printed code is more reliable than a rough measurement. Common sealed-beam references include H4651, H4652, H4656, H4666, H6054, and H6024. Match the full code whenever possible.
| What You See | Likely Headlight Family | Common Reference | Main Ordering Risk |
|---|---|---|---|
| Four small rectangular lamps | 4×6 | H4651, H4652, H4656, H4666 | Ordering four identical lamps when inner and outer positions require different functions |
| Two larger rectangular lamps | 5×7, also sold as 7×6 | H6054, H5054, 6052, 2B1 | Assuming the trade name confirms connector, depth, or exact fit |
| Two large round lamps | 7-inch round | H6024, 6014, 6015, PAR56 | Ignoring bucket depth, retaining ring, or adapter needs |
| Four smaller round lamps | 5.75-inch round family | Varies by high- and low-beam position | Mixing high-beam-only and dual-beam positions |
Count the Lamps and Confirm Each Position
A two-headlight vehicle usually uses one high/low-beam lamp on each side. A four-headlight system often uses outer low/high lamps and inner high-beam lamps. The housings may share the same outer dimensions but use different terminals, optics, or beam functions.
This is especially important with 4×6 systems. Do not order four matching lamps until you have checked the code and function in every position. See the detailed H4651 vs H4656 vs H4652 guide if your vehicle uses this format.
Measure the Lamp and the Space Behind It
Measure the lamp itself, not the bezel opening. Then measure the usable depth from the rear mounting surface to the nearest wiring, metal panel, or headlight bucket. A replacement can match the front dimensions and still fail to seat because its rear heat sink or connector is too deep.
Halogen Sealed Beam vs LED Headlight
Here is the bottom line: for a vehicle driven at night more than occasionally, an LED headlamp is the better choice. It draws less current, usually lasts longer, and with a well-designed optical unit puts more usable light on the road. Choose halogen sealed beam only when original appearance and lowest upfront cost outweigh the lighting benefits.
| Decision Point | Halogen Sealed Beam | LED Headlamp |
|---|---|---|
| Purchase cost | Usually lower | Usually higher |
| Original appearance | Best match for many restorations | Varies from period-style optics to modern projectors |
| Electrical load | Usually higher | Often lower, but check the rated watts and vehicle wiring |
| Road illumination | Predictable when the lamp and wiring are in good condition | Can improve useful light, but only with well-designed optics and correct aim |
| Cold-weather lens clearing | More forward heat may help melt snow | Some lamps need a heated-lens design for regular snow and ice use |
| Service | Replace the complete lamp | Replace the complete lamp unless the design has a serviceable light module |
| Fitment risk | Low when you match the original code | Check depth, polarity, pinout, retaining ring, adapters, and extra-function wiring |
Choose Halogen When Originality and Easy Replacement Come First
A quality halogen sealed beam still makes sense for a restoration, a vehicle driven only occasionally at night, or a route where a standard replacement must be easy to find. Before blaming the lamp for weak output, inspect the grounds, connectors, relay, charging voltage, lens condition, and headlight aim. Voltage loss in old wiring can make a good halogen lamp look poor.
Choose an LED Headlamp for Frequent Night Use
An LED sealed-beam replacement is the stronger choice for regular night driving, commercial use, or a vehicle that repeatedly consumes halogen sealed beams. Give beam evidence more weight than advertised lumens. IIHS testing across the passenger vehicle fleet shows why: low-beam illumination distances measured across rated headlight systems have ranged from about 125 feet on the poorest units to 460 feet on the best, a gap of nearly four seconds of reaction time at 50 mph. A controlled low beam that places light on the road is more useful than a brighter lamp that scatters light above the cutoff.
Judge the Beam Pattern Before the Lumen Number
Lumens describe total light output. They do not tell you where the headlamp sends that light. The road beam depends on the light source, reflector, lens, mounting position, and aim working together.
IIHS has rated headlight systems on passenger vehicles since 2016 using a technology-neutral method: halogen, HID, and LED systems can all score good, acceptable, marginal, or poor. Vehicles with good-rated headlights had 19% fewer nighttime single-vehicle crashes and 23% fewer nighttime pedestrian crashes than vehicles with poor-rated headlights. Acceptable and marginal headlights were associated with reductions of about 15% and 10%, respectively. A separate IIHS study released in October 2025 found that glare accounts for only about one or two out of every 1,000 nighttime crashes, reinforcing that usable forward visibility, not headlight color or brightness alone, is what correlates with safety outcomes. That is the standard to apply when comparing products, regardless of light source.
What a Useful Low Beam Should Show
- A controlled upper boundary that limits light toward oncoming drivers
- Even road coverage without a dark gap directly ahead
- Enough light toward the right shoulder for signs, pedestrians, and road edges
- A focused hot spot placed where distance vision needs it
- No large stray-light patches above the intended beam
What to Request From a Seller or Manufacturer
- Low- and high-beam wall photos taken at a stated distance
- Photometric test data or a report for the exact lamp model
- Effective output data measured after the lamp reaches operating temperature
- Confirmation of left-hand-drive or right-hand-drive beam requirements for the destination market
- A sample for an on-vehicle fit, wiring, aim, and road test before a bulk order
Reject a lamp if the seller provides only a raw lumen claim and beauty photos. Those items cannot confirm usable distance, glare control, or beam consistency.
What to Check for U.S. Road Use
Federal Motor Vehicle Safety Standard No. 108 covers original and replacement lamps for passenger vehicles, trucks, buses, trailers, and motorcycles. The standard sets photometric, color, marking, durability, and other performance requirements for headlamps, and it defines the two common headlamp types differently: integral beam headlamps, where the lens, reflector, and light source form one indivisible optical assembly, and replaceable-bulb headlamps, where the bulb is swapped inside a separate housing.
NHTSA addressed LED light sources directly in a February 2024 interpretation letter. The agency confirmed that manufacturers self-certify their vehicles and equipment to applicable federal standards, and that LED light sources are permitted in an integral beam headlamp as long as the complete headlamp meets FMVSS 108’s photometry and color requirements. In the same letter, NHTSA stated that no LED light source is currently permitted to be used in a replaceable bulb headlamp under that standard.
That creates a clear buying rule for a sealed-beam upgrade: choose a headlamp designed and certified as a complete optical unit, not a loose LED light source placed into a housing designed for a different light source. A 2025 consumer report and multiple news outlets covering the NHTSA letter confirmed that installing a replaceable LED light source into a housing not designed for it may violate federal law.
How to Read a DOT Claim
Do not treat “DOT approved” as proof that the U.S. Department of Transportation tested and endorsed the product. The U.S. system relies on manufacturer self-certification under the National Traffic and Motor Vehicle Safety Act. FMVSS 108 requires the “DOT” marking on the lens of covered headlamps, but a printed mark or online claim is only one item to check.
Before you buy, ask for the exact model number, clear photos of permanent lens markings, the manufacturer’s name, the applicable test report, and confirmation that the report covers the lamp being sold. Check your state inspection and use rules as well, since installation requirements can vary.
Primary references: NHTSA’s 2024 LED headlight interpretation, 49 CFR 571.108, and IIHS headlight ratings and research.
Confirm Mechanical and Electrical Fitment
A plug that connects does not prove the headlight is compatible. Run these checks before ordering.
- Size and shape: Match the old lamp code and physical format.
- Lamp count and position: Confirm two-lamp or four-lamp layout and label inner and outer positions.
- Beam function: Identify high beam, low beam, high/low beam, DRL, position light, and turn signal functions.
- Connector and pinout: Compare terminal count, terminal position, high beam, low beam, and ground. Some vehicles require an adapter or a pin change.
- System voltage: Verify 12-volt or 24-volt operation. Do not assume a truck uses the same voltage as a passenger vehicle.
- Polarity and grounding: Older vehicles and modified wiring may use a different ground arrangement. Test it before connecting the new lamp.
- Mounting depth: Leave room for the heat sink, connector, wiring bend, and dust protection.
- Retaining ring and tabs: Confirm the lamp seats flat and the ring closes without forcing the lens or housing.
- Extra-function wires: DRL and turn-signal features may require separate wiring beyond the main high/low connector.
- Electronic monitoring: On vehicles with bulb-out monitoring, confirm whether a decoder or load solution is needed. Many older sealed-beam vehicles do not use CAN bus monitoring, so check the vehicle instead of buying a decoder automatically.
For a mixed commercial fleet, use the more detailed 4×6, 5×7, and 7-inch fleet headlight fitment guide to build an approved vehicle list.
Choose Color Temperature for the Look and Route
Color temperature describes the appearance of the light, not the quality of the beam. A higher Kelvin number does not prove that you will see farther. IIHS notes that headlight color is not part of what determines a good, acceptable, marginal, or poor rating; beam distance and glare control are.
| Color Range | Appearance | Best Reason to Choose It |
|---|---|---|
| About 3000K–4300K | Warm to neutral white | Period-correct look, less blue appearance, or personal preference |
| About 4500K–6000K | Neutral to cool white | Modern appearance and clear contrast on dry roads |
| Above about 6500K | Noticeably blue-white | Mainly styling; verify that the emitted color remains within applicable requirements |
For most drivers who want a modern white LED, 5000K to 6000K is a practical starting range. If you want a classic look, choose a warmer option. In both cases, beam control matters more than Kelvin.
Match the Headlight to Your Driving Conditions
Frequent Rain or Fog
Choose a controlled low beam with limited upward scatter. A bluer-looking lamp does not solve poor wet-road contrast. Keep the lens clean and make sure the lamp is aimed after installation.
Snow and Ice
Ask whether the LED headlight has a heated lens if you drive through regular snow. LEDs often send less heat toward the front lens than halogen sealed beams, so snow may stay on an unheated lens longer.
Rough Roads and Work Vehicles
Check the mounting system, connector strain relief, sealing method, vibration test information, and warranty process. A strong beam does not help if the lamp moves in the bucket or the connector loosens.
Classic Cars
Look for a shallow housing, an original-style lens pattern, and a warm or neutral white option. Confirm that the rear of the LED unit clears the factory bucket before you buy.
Fleet Vehicles
Standardize only after one vehicle from each exact fitment group passes the installation and road test. Record the lamp code, connector, adapter, wiring change, aim method, and approved replacement SKU. This makes repeat orders and workshop service easier.
Five Checks Before You Buy
If a headlight fails any one of these checks, remove it from your list. A bright product photo cannot make up for poor fit, wiring, beam control, or documentation.
| Check | What to Review | What Good Looks Like |
|---|---|---|
| 1. Vehicle fit | Old lamp code, dimensions, position, mounting depth, retaining ring | The lamp seats correctly without cutting or forcing parts unless the modification is planned and documented |
| 2. Electrical match | Voltage, connector, pinout, polarity, rated power, extra-function wires | Every function operates correctly without flicker, overheated wiring, or warning errors |
| 3. Road beam | Low/high beam photos, photometric data, on-vehicle aim and road check | The low beam provides useful coverage without uncontrolled light above the intended beam |
| 4. U.S. road-use documents | Permanent markings, exact model number, manufacturer identity, relevant report, current state rules | The evidence applies to the exact lamp and intended installation |
| 5. Durability for your driving conditions | Sealing, thermal design, vibration information, lens material, warranty and replacement process | The design and support match the vehicle’s weather, road, and service conditions |
Once you have confirmed fit and wiring, compare 4×6 LED sealed-beam headlights, 5×7 / 7×6 LED headlights, and 7-inch LED headlights.
Common Claims That Can Lead You to the Wrong Headlight
“The Highest Lumen Number Is the Best.”
Total lumens do not show road placement, cutoff control, hot-spot position, or glare. IIHS-rated systems with similarly high advertised output have still landed at opposite ends of the 125-to-460-foot low-beam range described above. Compare the complete beam and test the aim.
“All 4×6 Headlights Are Interchangeable.”
Lamps with the same outer size may serve different positions and beam functions. Match the lens code, terminals, and inner or outer position.
“If the Plug Fits, the Headlight Fits.”
The pinout, voltage, ground arrangement, depth, retaining ring, beam function, and optical aim still need to match.
“DOT Approved Means the Government Tested This Product.”
U.S. vehicle equipment manufacturers self-certify compliance with applicable federal standards. Check the permanent markings and supporting documents for the exact model.
“6500K Is Always the Best Color Temperature.”
The right range depends on the driver, weather, lens, and optics. A 5000K lamp with a strong road beam can outperform a bluer lamp with weak control, since Kelvin rating plays no part in IIHS beam-performance scoring. Choose color after fitment, compliance, and beam quality.
How to Test a Headlight Before a Fleet or Wholesale Order
- Select one vehicle from each exact headlight configuration.
- Photograph the old lamp code, connector, wiring, and mounting bucket.
- Install a complete sample set, including both inner and outer lamps on a four-headlight vehicle.
- Test every function at operating voltage and allow the lamps to reach normal temperature.
- Aim the headlights using the vehicle or lamp manufacturer’s procedure.
- Check low and high beams on a wall, then conduct a safe road evaluation.
- Record the adapter, wiring steps, aim settings, and approved SKU for repeat installation.
For a LOYO fitment review, send the vehicle year, make, model, photos of the front lighting system, the code on each old lamp, connector photos, system voltage, and required quantity. This is enough to narrow the product family before you order a sample.
Frequently Asked Questions
Can I replace a sealed-beam headlight with an LED headlight?
Yes, if you use an LED sealed-beam headlamp that matches the original size, code, beam function, connector, voltage, mounting depth, and retaining system. For U.S. road use, check the lamp’s markings and compliance documents. A loose LED light source is not the same as an integrated LED headlamp. NHTSA has confirmed that LED light sources are not currently permitted in headlamps that use replaceable bulbs.
How do I know which sealed-beam headlight size I have?
Read the molded or printed code on the old lens first. Four small rectangular lamps often indicate a 4×6 system. Two larger rectangular lamps often indicate 5×7 / 7×6. Two large round lamps often indicate a 7-inch system. Confirm the choice with the code, dimensions, connector, and mounting depth.
Are 5×7 and 7×6 headlights the same?
They are common trade names for the same rectangular sealed-beam size family, often associated with H6054. The name alone does not confirm fitment. Check the old lamp code, connector, rear depth, retaining ring, and voltage.
Why can’t I order four identical 4×6 headlights?
Many four-headlight vehicles use outer lamps for low and high beam and inner lamps for high beam only. The units can share the same outer dimensions while using different optics or terminals. Check the code and function in all four positions.
Are LED headlights better than halogen sealed beams?
A well-designed LED headlamp provides more useful light with lower electrical draw. IIHS data shows vehicles with good-rated headlights have 19% fewer nighttime single-vehicle crashes and 23% fewer pedestrian collisions than those with poor-rated headlights, regardless of light source. Halogen remains a sound choice for a low-cost restoration or easy roadside replacement. Compare fit, beam control, road-use documents, and driving conditions rather than the light source alone.
What color temperature is best for LED headlights?
For a modern white appearance, 5000K to 6000K is a practical starting range. A warmer 3000K to 4300K option suits many classic vehicles. Color temperature is not part of IIHS beam-performance scoring, so beam pattern and aim affect road visibility more than the Kelvin number.
Do I need a CAN bus decoder for an LED sealed-beam replacement?
Only if the vehicle’s electrical monitoring system requires one. Many older vehicles with standard sealed beams do not use CAN bus bulb monitoring. Check for flicker, bulb-out warnings, or electronic load requirements before adding a decoder.
Do LED headlights need to be aimed after installation?
Yes. A direct-fit lamp can still sit at a different angle or place its optical center differently. Aim the headlights after installation and recheck them after suspension, tire-size, or ride-height changes.
Which Headlight Should You Choose?
For an older U.S. vehicle driven regularly at night, choose an LED sealed-beam headlamp that matches the old lamp code and clears all five checks: vehicle fit, electrical match, road beam, road-use documents, and durability for your driving conditions. The 2026 IIHS data is clear: good-rated headlights, whether halogen or LED, deliver 19% fewer nighttime single-vehicle crashes and 23% fewer pedestrian collisions than poor-rated ones. An LED headlamp gives you the best chance of hitting that target with lower electrical draw and longer service life.
Keep a halogen sealed beam when you value original appearance, low initial cost, and easy local replacement, for example, a weekend restoration that rarely sees night driving. For a four-headlight system, confirm every inner and outer position before ordering. For a modern molded headlight, follow the vehicle’s specified replacement bulb or assembly rather than using a sealed-beam guide.