Commonly confused terms
The pairs people mix up most — with the one-line difference and the calculator that settles it.
Total light a source emits (lm) vs how much lands on a surface (lx). The same lamp gives very different lux depending on distance and area.
Intensity in a single direction (cd) vs total output in every direction (lm). A tight spotlight is high-candela but modest-lumen.
Colour accuracy — how true colours look — vs colour appearance, warm or cool. A 2700K lamp can have high or low CRI; they are independent.
Beam angle is the bright core (out to 50% of peak intensity); field angle is the wider edge spill (out to 10%). Field angle is always the larger number.
Spot concentrates light in a narrow beam for accent; flood spreads it wide for general coverage. The beam angle is what separates them.
UGR rates indoor glare (offices, EN 12464-1); GR and TI rate outdoor and roadway glare (sports/road, CIE 112 & EN 13201). Different metrics, different standards.
Manufacturer terminology map
The same beam keeps getting renamed across catalogues. Here’s how the common labels line up.
| Generic term | Manufacturer labels | Beam / meaning |
|---|---|---|
| Very narrow spot | VNSP | ~8–10° — tightest accent beam |
| Narrow spot | NSP, Spot | ~15° |
| Spot | SP | ~25° |
| Narrow flood | NFL | ~30° |
| Flood | FL, MFL (medium flood) | ~40° |
| Wide flood | WFL | ~60° |
| Very wide flood | VWFL | 80°+ |
| Wall wash | Asymmetric, forward-throw | Even vertical wash down a wall |
| Regressed | Deep baffle, deep-set, recessed | Source set back behind the aperture to cut glare |
| Batwing | Type V / wide-spacing distribution | Even spread that allows wider fixture spacing |
Go straight to the calculator
Found your term? Jump to the tool that works with it.