Short answer: for a rifle, look at candela (how far the beam reaches) as well as lumens (how much light comes out). The SureFire M640DFT Scout Light Pro is the reach pick at 100,000 candela and 700 lumens, per SureFire; the Modlite OKW is close behind at about 69,000 candela; the Streamlight ProTac Rail Mount HL-X gives 50,000 candela and 1,000 lumens for much less; and the Streamlight TLR-1 HL is a floodier 1,000 lumens and 20,000 candela, well suited to rooms. For home defense inside a house, any of these is plenty; candela matters more outdoors and at distance.
Lumens vs candela, compared
Lumens, candela and throw
Lumens measure the total light a light puts out; candela measures the beam's peak intensity, which decides how far it reaches. The ANSI FL1 standard turns candela into throw (2 times the square root of candela, in meters), and Streamlight's published 447 m and 283 m figures match it exactly. A high-lumen, low-candela light floods a room; a high-candela light punches through a yard or field.
Mounting
Most rifle lights mount on Picatinny or M-LOK at the front of the handguard, often with an offset mount such as BCM's Scout mount so the light sits close to your thumb. See M-LOK vs KeyMod vs Picatinny and the accessories checklist.
Weapon lights, with today's prices
Lowest price across the stores we track:
SureFire M640DFT Turbo Scout Light Pro, tan
Pros
- 100,000 cd, 700 lm with SF18650 (SureFire)
- About 632 m throw
Cons
- Tan on this listing
Most reach
Modlite OKW-18350, FDE
Pros
- About 69,000 cd, 680 lm
- About 525 m throw
Cons
- No tailcap on this listing
High reach
Streamlight ProTac Rail Mount HL-X
Pros
- 1,000 lm, 50,000 cd (Streamlight)
- 447 m throw
Cons
- Less reach than the Scout Pro
Best value
Streamlight TLR-1 HL, FDE
Pros
- 1,000 lm, 20,000 cd (Streamlight)
- Wide, floody beam
Cons
- 283 m throw
Indoors
Streamlight ProTac Rail Mount 2
Pros
- Rail-mount long gun light
Cons
- Check output on the listing
Budget
Crimson Trace CWL long gun light
Pros
- 900 lumen LED, per the listing
Cons
- Candela not stated in the listing
Budget
BCM Gunfighter Scout light mount, M-LOK
Pros
- Offset M-LOK mount for SureFire Scout lights
Cons
- Mount only
Mount
Compare all accessories, or see the home defense build.
Frequently asked questions
What is the best weapon light for an AR-15?
The SureFire M640DFT Scout Light Pro for maximum reach; the Streamlight ProTac Rail Mount HL-X for value; the Streamlight TLR-1 HL for a wide indoor beam.
How many lumens do I need on an AR-15?
Indoors, the 700 to 1,000 lumen lights here all give plenty of light. Outdoors, look at candela: higher candela reaches farther.
What is the difference between lumens and candela?
Lumens is total light output; candela is beam intensity, which sets how far the light reaches.
How do I calculate a light's throw?
Under the ANSI FL1 standard, throw in meters is 2 times the square root of the candela; 50,000 candela gives about 447 m.
Where should I mount a light on an AR-15?
At the front of the handguard, where your support-hand thumb can reach the switch, often on an offset mount.
