Weapon Light Buyer's Guide: Lumens, Candela, and Mounting

Every weapon light on the shelf leads with a lumen number, because lumens are the number people know. It is also the number that tells you the least about whether the light will do what you need. The spec that matters more is candela, and most shoppers have never heard of it.

Lumens and candela, in plain terms

Lumens measure total light output. Think of it as how much light the emitter produces in every direction combined. More lumens means more light in the room.

Candela measures intensity in the center of the beam. Think of it as how hard the light pushes down range. Candela is what determines how far you can see and identify.

Two lights can both claim 1,000 lumens and behave completely differently. A wide, floody 1,000 lumen light will light up a whole garage and see almost nothing at 75 yards. A tight 1,000 lumen light with high candela will reach the back fence and give you a smaller pool of usable light up close.

Neither is wrong. They are tools for different distances, and the right answer depends on the longest distance you actually need to identify at.

Rough numbers to shop against

• Indoor, home defense pistol. Somewhere around 500 to 1,000 lumens is plenty, and roughly 10,000 to 20,000 candela covers typical household distances comfortably. Going much brighter indoors mostly buys you more light bouncing back off white walls into your own eyes.
• Outdoor or property use, rifle. Candela is the number to chase. Fifty thousand and up starts to matter, and lights built for reach will trade beam width to get it.
• Mixed use. Look for a light with both a usable spill and a defined hot spot, rather than the highest single number in either column.

If a manufacturer publishes lumens but not candela, that is worth noticing.

Lights & Lasers

Surefire X300 Turbo- B LED Pistol Light, 650 Lumens, 66,000 Candela X300T-B-TN

$359.99

View productShop Lights & Lasers

Runtime and batteries

Runtime figures are usually quoted at full output, and many lights step down after a couple of minutes to manage heat. That is normal and sensible, but it means the number on the box is not the number you get.

• CR123A. The long standing standard. Excellent shelf life, works in cold, available anywhere, and you buy them forever.
• Rechargeable 18650 and proprietary packs. Cheaper to run and often higher output, at the cost of remembering to charge them and of a battery that ages.
• AAA and CR2. Found in the smallest pistol lights. Convenient, but expect shorter runtime and lower output.

Whatever you pick, put a fresh battery in on a schedule you can remember, not when the light starts looking dim. A defensive light gets used once, unexpectedly, after sitting untouched for a year.

Switching, which matters more than the specs

The best light in the world is useless if you cannot turn it on under stress without changing your grip.

• Pistol lights use ambidextrous paddles or toggles at the rear of the light, worked with the support hand thumb or trigger finger. Try the motion with your actual grip before you buy. Some combinations of hand size and pistol simply do not work.
• Rifle lights use a tail cap button, a remote pressure pad, or both. A pressure pad mounted where your support thumb naturally rests is worth the extra cable management.
• Momentary versus constant. Momentary means the light is on only while you press. Both modes have their place, and a light that gives you both without a mode cycle is doing it right.
• Strobe and mode cycling. A light that hides constant on behind a sequence of clicks is a liability. Simpler is better.

Mounting it properly

Mounting is where a good light becomes a bad experience. Three things to get right:

1. The interface. Rifles are mostly M-LOK or Picatinny these days, and a lot of lights ship with one and not the other. Check before you order, and check the mounts section if you need an adapter. Pistols use a rail on the dust cover, and there is more than one pattern, so confirm your frame matches the light.
2. The position. Far enough forward that the beam is not clipped by the muzzle device or a suppressor, and close enough that your support hand reaches the switch without moving. Those two goals fight each other. Mount it, dry practice with it, then move it.
3. The torque. Manufacturer spec, with a torque wrench. A light that walks under recoil will loosen and eventually fall off.

Things worth checking before you buy

• Recoil rating. A handheld flashlight bolted to a rifle is not a weapon light. Weapon lights are built to survive recoil, and the ones that are will say so.
• Water and dust rating. An IPX rating tells you what it survived in a lab. It is a floor, not a promise.
• Weight and where it sits. Weight at the far end of a handguard changes how the rifle handles more than the same weight near the receiver.
• Holster compatibility. If it is going on a carry pistol, the holster has to be molded for that specific light. Order both together.
• Infrared, if you run night vision. A visible light and an IR illuminator are different tools, and a few units do both. See night vision if that is the direction you are heading.

Where to go next

Current stock is in lights and lasers, mounting hardware is in mounts, and if you are assembling a defensive setup from scratch, start with the beginner handgun setup guide.

Using a light well under pressure is a trained skill, not an instinct. Working a light into your draw and your movement is one of the things our lessons cover.