How to choose a headlamp: lumens, beam distance and modes

A headlamp is the most practical light you can own – your hands stay free and the beam points exactly where you look. But there are a lot of specs and the marketing numbers often mislead. Let us break them down so you buy a headlamp that actually serves you.

The lumen is the unit of luminous flux – how much light the source puts out in total. But more lumens does not automatically mean better. For reading a map at camp 20–50 lm is enough, for a night trail run you want 200–400 lm, and for work or navigating terrain a reserve up to 500 lm helps.

More important than the maximum is how long the headlamp runs at a sensible output. Manufacturers like to quote the highest figure, which the battery holds for a few minutes before the light dims to avoid overheating. That is called step-down, and it is not a fault – it protects the LED and the cell.

On the HL1 the range is on full display. Max gives 2,000 lm for four hours, Standard 800 lm for thirty hours, Eco 200 lm for up to 230 hours. Three numbers, three completely different ways of using it – and the lowest is the one you will have switched on most often.

A narrow spot reaches far and suits running or navigation, a wide flood lights up your surroundings and campers or DIYers will appreciate it. The most versatile headlamps do both and switch between them – the HL1 has a spot beam, a flood beam and a combination of the two.

Beam distance is not calculated from lumens but from luminous intensity in candelas. The HL1 has 5,626 cd, which under the ANSI FL1 standard works out to exactly 150 metres. How to calculate it for any light we cover in the article on lumens and luminous intensity – it is a single square root, and it pays to know it, because beam distance is where catalogues exaggerate the most.

Runtime is the spec that usually decides the purchase – and the hardest one to compare, because every manufacturer quotes it at a different level. The rule is simple: look for the runtime of the mode you will actually use, not the strongest or the weakest one.

Cell capacity feeds into it. The HL1 uses a 21700 with 4,000 mAh, that is 14.8 Wh, which is the upper limit for headlamps today. The HL2 has a built-in 1,000 mAh cell, 3.7 Wh – a quarter of that, but at a quarter of the weight and size. It charges in an hour and a half, so you can top it up during a break.

The second thing to ask about is a battery indicator. A headlamp that dies on you without warning is worse than one with a shorter runtime whose end you can see coming. The HL2 shows battery status.

On your head you feel every gram – and above all you feel where that weight sits. A headlamp with the cell up front bounces when you run, and you end up tightening the strap until it presses. One with the battery box at the back sits more calmly, but the whole thing is bigger.

The HL2 handles the size-to-output ratio best. The module is 66 × 25 × 31 mm, the whole thing weighs 136 grams, and the light head tilts through 180 degrees, so you can light up your hands without tipping your head. The module also comes off the strap completely and clips onto steel with its magnetic base – the headlamp turns into a work lamp.

The HL1 is bigger and heavier, but it pays for that with output, capacity and things a smaller headlamp simply cannot do. The ideal is to own both and take whichever fits the trip.

An IP rating matters more on a headlamp than on a handheld light, because it sits on your head and takes the rain the whole time. The HL1 is IPX6, resistant to powerful jets of water; the HL2 is IP68, dust-tight and good for continuous immersion. What those numbers actually mean we cover in the article on IP ratings.

The second enemy is frost. In winter a Li-ion cell delivers less current and the headlamp drops to a lower mode on its own – once it warms up, the output comes back. For a multi-hour winter trip it pays to wear the headlamp under a hat or keep a spare light in a warm pocket.

Two features get overlooked when choosing, yet they get used daily. Red mode preserves your dark adaptation and does not dazzle the person opposite you – at camp that is the difference between peace and swearing from the next tent. And a high colour rendering index means you can tell the real shade under the headlamp; the HL1 has CRI 95. We cover both in the article on warm and cool white.

• What will I use it for most? Pick the mode you will actually run – and its runtime, not the maximum.
• Do I need to see far, or right under my hands? Spot, flood, or switchable between the two.
• How long will I be away from a socket? Capacity in watt-hours, not mAh, and the option to top up during a break.
• In what weather? IPX6 is enough for rain; worry about IP68 only if you will actually submerge it.

One last piece of advice. Buying a headlamp by the biggest number on the box is the fastest route to disappointment. Take the one with a sensible runtime in the middle mode, one that fits your head and that you are not afraid to take out in the rain. If you mainly want it for running, have a look at the article on night running – the demands there are a little different from hiking.