Headtorch ratings explained: lumens, beam distance and runtime

Choose a headtorch by the brightness you can use for the whole walk, its beam and its battery system. The biggest lumen number on the box tells only part of the story.

Understand the ratings

• Lumens (lm) describe total light output. More lumens usually mean more light, but beam shape matters too.
• Beam distance (m) describes reach. A wide beam helps you see the ground nearby; a focused beam helps pick out more distant features.
• Runtime belongs to a particular mode. Under the ANSI/PLATO FL 1 method described by Petzl, the endpoint is 10% of the initial measured output. A long runtime does not mean full brightness throughout.
• Constant output holds brightness steadier; other lamps gradually dim. Reactive modes adjust output to the surroundings, so their runtimes can vary.
• IPX4 means splash resistance, useful in rain. It does not mean the lamp can be submerged.

Read the mode, brightness and runtime together

Petzl’s SWIFT RL CLASSIC gives a useful example in standard lighting:

Its 1,200 lm boost lasts six seconds. That is a short burst, not the setting for a whole night walk. Compare equivalent modes when choosing between lamps, then allow spare battery capacity for stops and delays.

Check a second-hand headtorch

• Ask for the exact model and its manual, then check which batteries or charging cable it requires.
• Inspect the battery compartment for corrosion, cracked plastic and damaged seals. Check that the strap holds its adjustment.
• Test every mode, the switch, lock function and charging. A lamp turning on briefly does not prove that an ageing battery will last the advertised time.
• Include a replacement battery or missing cable in the full cost.

What I would carry

I would pack a charged headtorch, a compatible spare battery or small backup light, and enough power for the return trip. I would use a comfortable walking mode and save the brighter beam for checking a junction. Practise the controls before you need them in the dark.

For the rest of your kit, see our guide to keeping hiking gear dry.

Sources and photo credits

Source checks: 28 September 2026.

• Petzl: understanding headlamp burn times
• Petzl: SWIFT RL CLASSIC specifications

Historical activity photograph from Joshua Tree National Park, USA. Photo: Boy Scout Trail at Night with Hiker using a Headlamp (40503845552).jpg — Joshua Tree National Park. Public domain. Resized for display.