After getting burned by a “90,000 lumen” torch that did maybe 800 real lumens for ten seconds, I stopped trusting the number on the box entirely. What I trust instead is a standard called ANSI/NEMA FL-1. If you learn to read it, you’ll never get fooled by a headline number again.
What FL-1 is
FL-1 is the flashlight industry’s measurement standard — the agreed rules for how you measure and report what a light does. The point of a standard is that it takes the maker’s imagination out of it. Instead of “it feels really bright,” FL-1 says: measure this number this way, report it on these icons, so a buyer can compare two lights honestly.
When a reputable maker prints FL-1 figures on the package, you’ll see a row of little icons. Each one is a promise measured a defined way. Here’s what they mean and which ones actually matter.
The five numbers that matter
1. Lumens (light output). Total light the thing puts out, measured a defined way — not a peak flash. Useful, but on its own it’s the most over-weighted number on the box. A high lumen figure means nothing if the light can’t hold it.
2. Runtime to 10% (the one nobody reads). This is the number that would have saved me. FL-1 runtime is measured to the point where output falls to 10% of the starting level. So if a light starts at 1,000 lumens and the runtime figure is 2 hours, that’s 2 hours before it’s dropped to 100 lumens. My cheap torch would have shown a runtime-to-10% of well under two minutes if it had ever been honestly tested — because that’s how fast it collapsed. Always read lumens and runtime together. One without the other is half a story.
3. Peak beam intensity (candela) and throw. Candela measures the intensity of the brightest part of the beam, and from it you get throw — how far the useful light reaches. The physics is clean: throw in metres ≈ 2 × √(candela). A light with high candela and modest lumens is a thrower (tight, far-reaching); high lumens and modest candela is a flood (broad, close). The number tells you the beam’s shape, which matters as much as its brightness.
4. Impact resistance. The height in metres the light survives being dropped onto concrete in testing. For a carry light that lives in a pocket and gets dropped on driveways, this is a real-world number worth a glance.
5. Water resistance (IP rating). IPX4 is splash-resistant; IPX7 survives brief submersion; IPX8 goes deeper. If your light rides through rain, snow or a creek, this is the difference between a working light and a paperweight.
How to read a box in ten seconds
Here’s the gut check I run, and you can do it in the store or on a listing:
- Is there an FL-1 reference and a row of measured icons, or just one giant lumen number? A row of FL-1 figures is a maker telling the truth on the record. A lone hero number with no runtime, no candela, no IP, is the tell. That’s the box that lied to me.
- Find the runtime figure and pair it with the lumens. “1,000 lumens” with “2 hours to 10%” is honest. “90,000 lumens” with no runtime listed is fantasy.
- Check candela if you care about reach. Run it through the throw formula or just trust that high-candela-low-lumen means thrower, high-lumen-low-candela means flood.
- Glance at impact and IP for how rough your life is on gear.
When a maker doesn’t publish FL-1 figures, that’s information too. Sometimes it’s a small honest brand that just didn’t pay for testing — but a screaming lumen number with nothing to back it almost always means the number is the product, not the light.
Why this protects your money
The whole reason marketing lumens exist is that “biggest number wins” is how most people shop. FL-1 is the antidote. It forces the conversation onto numbers a maker has to stand behind. Once you read lumens-with-runtime, candela-for-throw, and IP-for-durability, the hype number on a cheap torch just looks like what it is — a font.
I lean on FL-1 for everything on this site, and nowhere harder than the battery-and-output guides. If you want to see honest figures applied to real lights — regulated output, published runtime-to-10%, and the cells and chargers behind them — start with the best 18650 flashlights guide. Learn the standard once, and no box will ever lie to you again.