Editorial guide
Flashlight terms explained
A plain-English glossary for making sense of the specs on a light box or product page.
A quick reference to output, beam, color and test terms.
Output and intensity are different labels
Lumens report total luminous flux. Candela measures intensity in one direction. Together, they describe different parts of a beam.
ANSI/PLATO beam distance uses a 0.25 lux threshold under its stated method. You will often hear it called throw. Treat it as a measurement point, not a guarantee that every object will be easy to identify there.
Read a specification line as a group
A large lumen figure cannot tell you whether the beam is wide or concentrated. Read lumens beside candela, beam distance and the described beam shape.
Two lights can distribute a similar total output differently. The useful comparison is the combination of output, directional intensity and the stated test distance, not one isolated maximum number.
Beam shape, color rendering and color temperature
Beam shape describes how light is distributed. A beam can be wide, narrow or somewhere between, so read the maker's wording alongside the numbers.
CRI describes color fidelity against a reference. CCT describes the apparent color of a light source in correlated color temperature. They are useful color terms, separate from output and beam reach.
Four common specification mistakes
More lumens do not automatically mean more reach. More candela does not mean more total output. The two measurements answer different questions about the same beam.
A beam-distance figure marks the stated 0.25 lux test threshold, not a promise that every object will be easy to recognize at that distance. CCT and CRI are separate too: apparent color and color fidelity are not interchangeable.
A useful comparison order
Start with the output mode you expect to use, then read lumens, candela and beam distance together. Use the beam description to decide whether that combination sounds broad, concentrated or balanced.
Check runtime for the same mode rather than comparing one light's maximum output with another light's lower sustained mode. If color matters, add CCT and CRI after the beam and runtime comparison.
lumens (lm) total luminous fluxcandela (cd) intensity in a directionbeam distance (m) stated test threshold
| Term and meaning | Unit | Read alongside | Exact sources |
|---|---|---|---|
| Lumens: total luminous flux. NIST | lm | Candela, beam shape and runtime. | NIST, Realization of the Lumen |
| Candela: luminous intensity in a direction. NIST | cd | Lumens and beam distance. | NIST, Luminous Intensity |
| Beam distance: 0.25 lux threshold under ANSI/PLATO method. PLATO | m | The stated test method. | PLATO, About the standard |
| CRI: color-fidelity metric. DOE | Ra / index | CCT and the maker's color description. | U.S. Department of Energy, LED basics |
| CCT: apparent source color descriptor. DOE | K | CRI, output and beam reach. | U.S. Department of Energy, LED basics |
Source notes
Manufacturer and standards sources for the facts on this page.