Gear ·Research-basedPublished November 2, 2026

Lumens vs Candela vs Runtime: Reading Flashlight Specs

Disclosure: DanPicks may earn a commission if you buy through links on this page. It does not change the price you pay or what I write. This is a research-based article: I compiled it from manufacturer specs, third-party measurements and public reviews, and I have not tested these products myself. How I review.

Short answer: Lumens tell you how much light comes out, candela tells you how far it reaches, and runtime tells you how long it lasts, but box numbers are best-case figures: look for an independent 30-second measurement and the step-down behavior before you trust a big lumen claim.

This is an explainer built from published standards summaries, manufacturer spec sheets and independent measurements. Every example number below comes from a source listed at the bottom.

The five numbers on a flashlight box

FL1 timings above are from Petzl’s summary of the standard. Streamlight notes the standard is voluntary, so not every brand follows it.

Lumens vs candela: two lights, two jobs

Lumens and candela pull in different directions. The same LED can be put behind a tight reflector (high candela, long throw) or a wide one (lower candela, wide flood).

The E10 2.0 has fewer lumens than the Baton 4 but over four times the throw. If you want to see down a trail or across a field, look at candela. If you want to light a room or a campsite, look at lumens and beam width.

Quick rule: because throw is the distance where light falls to 0.25 lux, throw in meters = 2 × √candela. That’s why candela is the number behind the throw figure: 2 × √127,806 ≈ 715 m.

Why big lumen numbers mislead

1. Turbo doesn’t last. Most small lights step down to protect the battery and LED from heat. Acebeam’s own page says the E75’s 4,500 lm turbo steps down to 1,500 lm.
2. The 30-second number can be far below the box. Zeroair measured the Nitecore EDC35 at 4,231 lm at turn-on but 983 lm at 30 s in its top mode. The Nitecore EDC07 measured 75% of its claim at 30 s.
3. Some brands are close to their claim. Zeroair measured the Olight Baton 4 at 91.5% of its claim at 30 s; 1lumen measured the Wurkkos FC11C at 975 of 1,200 lm.

So the useful question is not “how many lumens?” but “how many lumens after 30 seconds, and for how long?”

Runtime: read the fine print

• FL1 runtime runs until output falls to 10% of the start. A light can technically “run” for 90 hours on its lowest mode while being useless for most tasks after the first hour on high.
• Look for a runtime graph in an independent review. It shows the step-downs: how long turbo lasts, what level it settles at, and when it drops off.
• Battery size drives runtime: a 21700 cell (around 5,000 mAh in the Acebeam E75) holds far more than a 16340 (850 mAh in the E10 2.0).

IP ratings in one minute

• IP67: dust-tight and survives immersion in 1 m of fresh water for up to 30 minutes.
• IP68: better than IP67, but the depth and time are set by the manufacturer, so read the brand’s spec. Acebeam lists IP68 as 2 m for 30 minutes on the E75.
• IP54 (Nitecore EDC23): splash-resistant, not for submersion.

Battery types you’ll see

A five-minute checklist before you buy

1. Decide the job: far (candela) or wide (lumens).
2. Find an independent review with a 30-second lumen measurement and a runtime graph.
3. Check whether the battery is standard, built-in or proprietary.
4. Check the IP rating against where you’ll use it.
5. Compare the price on the brand’s own store.

Put it to use

• Best EDC flashlights under $50
• Acebeam vs Olight vs Nitecore
• Acebeam flashlights: which model to buy

Sources

Written by Dan. Spotted a mistake? Tell me and I will fix it and note the correction.