How to Choose a Headlamp

When selecting a headlamp, you should first consider its size and weight. You'll also want to compare a trio of performance attributes:

• How far can it cast a beam?
• What kind of battery life can it provide?
• How intense (or bright) is its light source?

To answer the first two performance questions, you can:

1. Visit headlamp product pages on REI.com to view the spec charts and, when available, new performance charts provided by individual manufacturers. You can click on three sample charts offered below.
2. Visit an REI store and compare these performance charts found on the packaging of most headlamps.

To explain the last question on light intensity—which is the technical term for what most call "brightness"—we need to define some terms and clarify some details.

Reading Headlamp Charts

First, here's a quick-start guide to understanding headlamp performance charts.

1. Maximum Beam Distance

Look for the highest mode the headlamp offers and the "fresh batteries" line, indicated by "t = 0h." That's international shorthand for "time = zero hours of battery use."

Where those two lines intersect you'll see a number. That's the maximum distance (in meters) the headlamp can throw "usable light." Usable light is the equivalent of a full moon's light on a clear night (measured as 0.25 lux—more on that number later).

Results from these examples:

• Headlamp A: 26 meters (85 feet)
• Headlamp B: 70 meters (230 feet)
• Headlamp C: 35 meters (115 feet)

So if a powerful beam (not weight, not battery life) is your priority, the charts show that Headlamp B offers a stronger beam.

2. Battery Life

Look for the headlamp's lowest mode. This is the setting most people use for routine chores at night. Then look for the number of hours on that line.

Results from these examples:

• Headlamp A: 160 hours (160 h)
• Headlamp B: 142 hours (142 h)
• Headlamp C: 120 hours (120 h)

Not surprisingly, we see that the headlamp in this group that throws its beam the shortest distance (Headlamp A) also offers the longest battery life. So if long battery life is your priority, consider Headlamp A.

Charts include additional numbers that show how lights perform in different modes (low and medium as well as high) and at different stages of battery use (t = 0h30 or 0:30h or 0.5 h indicates 30 minutes of continuous battery use; t = 10h refers to 10 hours of continuous use). Use the references we suggest above for simple product-to-product comparisons.

Note: All figures are provided by manufacturers and are based on a uniform testing method. Your results may vary.

3. Light Intensity ("Brightness")

Light intensity is measured in units called lumens and lux. REI regards lux as a more useful measurement.

Note: "Brightness" is not viewed as a technical term within the lighting industry. Lighting professionals regard "brightness" as a subjective interpretation of light intensity. Excessive brightness is often described as "glare."

Here are basic definitions of lumens and lux:

Lumens: The total output from a light source as it radiates out in all directions. Lumens indicate how intensely a light glows.

Most headlamp packages display lumens. (A 100-watt light bulb emits about 1,750 lumens.) However, because manufacturers measure lumens differently, you can't count on apples-to-apples comparisons between brands.

Lux: The quantity (or density) of light that falls on a surface being illuminated. In other words, lux is measured where the light goes.

Lux has replaced footcandles as unit of measure for lighting. Lux, measured with a light meter, indicates the adequacy of light that reaches a surface or area—for example, on a trail in front of your feet at night.

Headlamp packaging excludes lux figures. REI, meanwhile, favors lux as a gauge of light intensity because this is the purpose of a headlamp—to channel light to an area where a task is being conducted. So we list lux figures, calculated using specifications provided by manufacturers, under "Lux @ 2 meters" on our spec charts.

Lux @ 2 meters: On flat surfaces, the light of a full moon shines at an intensity of 0.25 lux. Lighting pros call this the "moonlight standard."

If full moonlight equals 0.25 lux, that means 1 lux (measured at a distance of 2 meters) is 4 times brighter than a full moon, and 10 lux is 40 times brighter. Higher lux numbers indicate which headlamps can provide more brightly illuminated surfaces.

Why 2 meters (6'6")? On average, it's the angled distance—from your forehead to ground in front of your feet—needed by most people to illuminate a trail at night. Since many outdoor-oriented people have experienced walking at night while wearing a headlamp, 2 meters was chosen as a practical, easy-to-grasp distance of measure.

Why not just state brightness in watts, as is commonly done with household light bulbs?

A watt is a measurement of a lamp's power consumption; a lumen is a measurement of light output; lux measures how well a light source illuminates a surface or area.

Standard household incandescent bulbs convert most of their energy consumption (up to 90 %) into heat (or, infrared light) rather than visible light, making them less energy-efficient. An energy-efficient, cool-to-the-touch 1-watt LED could actually produce more light than an incandescent bulb with a higher wattage.

To recap: Lamps emit light, measured in lumens (how it glows). The density of light that falls on a surface is measured in lux (where the light goes).

A Few Words on Technical Details

Lighting is an amazingly technical topic. Some aspects of lighting, even among professionals, are open to debate and interpretation.

Lighting has its own vocabulary, and lighting technicians may argue about the subtleties and nuances of their craft with the fervor of theologians discussing their views of religion. (We may be exaggerating a little, but not by much.)

At the end of this article, we address some of these finer points as they relate to portable lighting used for recreation and emergency situations. While significant, most are probably beyond the interest of many consumers who are simply looking for a quick way to compare lights.

Headlamp Features

Lamp types: Common light sources for headlamps include:

• Xenon, halogen or krypton bulbs: Incandescent bulbs that contain a pressurized gas such as xenon. When introduced into a bulb's glass casing, these gases prevent oxidation of the filament, controling soot buildup that tends to darken traditional bulbs. As a result, these bulbs burn with high intensity.

• High-output LEDs: 3-watt LEDs rival the brightness of pressurized-gas bulbs; 1-watt LEDs produce a light intensity that matches up well with standard incandescents—only they use much less battery power.

• Incandescent bulbs: Traditional bulbs filled with an inert gas, such as argon; they usually cast farther-reaching beam and produce higher lux numbers than standard LEDs.

• LEDs: They excel in energy efficiency while offering good, all-purpose proximity lighting for camp chores, map-reading and close-up work.

LEDs (light-emitting diodes, a simple type of semiconductor) are the dominant lamp type used in headlamps—and they are growing more prevalent in flashlights as well.

Key benefits of LEDs:

• They drain batteries 3 to 5 times slower than traditional incandescent bulbs.
• LEDs can have a life span of up to 100,000 hours; an incandescent bulb may burn out in less than 40 hours.
• With no glass or filament to break, LEDs are very tough and ideal for rugged use.

Pressurized-gas bulbs still lead the pack in terms of highest lux numbers, but high-output LEDs continue to evolve and narrow that gap. It is widely expected that future generations of LEDs will outperform all incandescents.

Beam pattern: The parabolic reflectors that surround lamps influence how effectively a headlamp channels light. You can choose from three general pattern options:

• Flood (or fixed; wide): A single beam width; no adjustability. Good for slower-paced general tasks in camp or while walking.

• Spot (or focused): LED models with specialized lenses that condense the beam into a spotlight, throwing a narrow beam a long distance. This is often preferred during route-finding, running, paddling or fast-paced hiking.

• Adjustable: Beam width can range from wide to narrowly focused or in-between. It's a nice feature. A climber looking for the next pitch would use a spot beam; to study a map, a flood beam.

Regulated output: Some lights include a regulated power supply, and it can be a desirable feature.

Unregulated lights start bright then progressively grow dimmer as they draw power from a set of batteries. Batteries tend to last longer when used in unregulated lights.

With a regulated power supply, lights maintain a steady, near-peak brightness level throughout most of the batteries' life cycle. Near the end, though, light output will drop off abruptly and significantly. In some cases, the light will simply go dark. Thus you may be forced to change batteries in the dark.

Modes: Simple lights provide a single setting — quite sufficient for general-purpose use. Other models offer two or more brightness levels — in some cases, as many as six (low, medium, high and beyond). You may rarely use it, but having the option to throw an extra-strong beam on demand is often a reassuring luxury.

Boost mode: Some lights offer a "boost" mode that temporarily projects the unit's most powerful beam possible. It lasts about 20 seconds max (to minimize the drain on batteries and avoid causing the light to overheat). Climbers appreciate having access to this option when searching for a pitch in fading light; kayakers like it when surveying the water for rocks in dim light.

Strobes: Valuable during emergencies or signaling for rescue. A few lights give you the option of slow flash or fast flash. The strobe mode drains less battery power than any other mode.

Weight: Typically, the simpler a headlamp—a single lamp, one or two modes, AAA batteries — the lighter the unit. High-output (very powerful) headlamps sometimes require larger batteries (AA) or more of them, which increases weight. Extra features (such as a hybrid light that features a pressurized-gas bulb and multiple LEDs) usually also add to the cost.

Functionality: If you're able to visit a store and examine headlamps in person, consider how the light switches on and off. Do any models seem more likely to you to become inadvertently switched on inside your pack? Or, if you plan to use it in cold conditions, how easily could you switch it on wearing gloves? Is a tool required to change batteries? Some headlamps are inventively designed so one part of the headlamp can be used as a tool to open the battery compartment.

Batteries: Many headlamps come packaged with batteries included—usually AAA alkaline models; some use larger AA batteries. A few lights work with lithium or lithium-ion batteries.

IMPORTANT: Do not attempt to use lithium or lithium-ion batteries with any light unless manufacturer instructions state that the specific light is designed to operate with lithium batteries. If not, you run the risk of damaging, even ruining, a light by mismatching it with lithium batteries.

Alkaline batteries lose power quickly in temperatures below 20° F. (Lithium batteries, on the other hand, perform well in the cold.) To extend the life of alkaline batteries in the cold, carry them under clothing during the day and sleep with them inside a sleeping bag at night.

Another option: Choose lights with remote battery packs that can be kept under clothing or a hat.

Random Tips

Stargazing: A red, blue or green lens (or filter or bulb) is an option for consulting a map or chart at night. Red light preserves your night vision but decreases your ability to read. Blue and green lights increase your ability to read but decrease your night vision.

International travel: Lights with long battery life (such as LEDs), common battery types or rechargeable batteries make good choices. Pack replacement bulbs and spare batteries.

Technical Q&A

Q: Is a headlamp with a strong beam always the most intense (brightest) light?

A: Not necessarily. A laser beam is a very powerful beam of light that can travel long distances, but it only casts a pinpoint of light—too narrow to usefully illuminate a surface or area.

Still, for headlamps and the varying beam widths they offer, beam strength is a useful, general indicator of overall brightness.

And here's a technical footnote: Headlamps with a strong center point of light may have an advantage in this test. The protocol does not measure the strength of the light output outside of the center point, a potential disadvantage for lights that offer only a wide beam and an advantage for lights with only a spot beam.

Q: How do lumens and lux differ technically?

Lumens (the total output, in all directions, of a light source) is measure of "luminance"—which is a more scientific way of expressing how a light glows.

One way lumens are measured is with the use of a sphere. The sphere captures a light's total output as it radiates in all directions.

This reflects one reason why REI puts less emphasis on lumens as a measure of light intensity. How effectively a light's total lumens are focused, or channeled, to a surface or area determines the performance level of a headlamp. This is determined by the structure of the headlamp's reflector and lens.

Two headlamps, for example, may emit the same number of lumens, but one is designed to provide a wide beam and the other a narrow spot beam. The two beam patterns will result in two different experiences despite the identical lumen count. And if a headlamp has a translucent casing, some lumens are lost as they radiate in a vertical or backwards direction instead of being channeled forward.

Lux, meanwhile, is a measure of "illuminance." It is measured on a surface or at task area where a headlamp is channeling its light—the area that you want to be illuminated. This is why REI values lux numbers as a more revealing measurement of a headlamp's capabilities.

Q: What is the rationale that led to the creation of headlamp performance charts?

A: Retailers and major headlamp manufacturers recently agreed that shoppers needed an easier way to compare performance attributes of different headlamps.

Major manufacturers thus agreed to a uniform testing method (engineers call it a "protocol") that consistently measures beam strength and battery life for headlamps. The results are then configured in a chart format and included on all headlamp packaging. Unfortunately, each manufacturer take a different design approach to their charts, so chart-to-chart information is not in uniform alignment.

At the core of this protocol are two baseline measurements:

1. The light of a full moon on a clear night. This is considered to be the minimal amount of "usable light" needed to perform an activity. Among lighting engineers, it's known as the "moonlight standard." Technically, this amount of light is expressed as 0.25 lux.

2. A distance of 2 meters. Or about 6'6". Since the average U.S. male (according to a 2002 report from the National Center for Health Statistics) stands 5' 9½" and the average female, 5' 4", a headlamp is still considered functional if it can project usable light (moonlight) a distance of 2 meters—roughly from the wearer's head to the trail ahead of their feet.

Q: How are headlamps tested?

A: Each manufacturer tests its own lights and provides its own numbers on its packaging. The process (protocol) works something like this:

• A headlamp, equipped with fresh batteries at 70°F, is switched on.
• A light sensor is moved away from the light until the center point of its beam registers 0.25 lux (the equivalent of a full moon's light) on the sensor. This distance is recorded as the farthest point the headlamp can project usable light (and shown on product packaging as t = 0h, or time = zero hours of battery use).
• As batteries drain and the light dims, the sensor is progressively moved closer to the headlamp to maintain a measurement of 0.25 lux (A full moon's light, which is considered the minimum usable light needed to be able to complete tasks at night).
• Distance measurements are also taken at 30 minutes (t = 0h30), representing an evening of routine in-camp usage, and 10 hours (t = 10h), representing all-night use. The distances recorded reveal the beam strength available from a light during a battery life cycle.
• Measurements continue until the 0.25 lux reading reaches the 2-meter mark. Once a reading of .25 lux cannot be maintained at 2 meters, the test is complete. This provides the estimated battery life of the headlamp.

Back to Top