candela in, footcandles on the deck.
or just type numbers below — nothing is uploaded, the file is read in your browser.
assumes all lumens inside the beam angle — real fixtures spill; treat as an estimate.
additive only where beams fully overlap.
inverse square law runs everything: E = cd/d². everything else is geometry.
seven panels off one law. trim height and setback give throw distance and tilt; candela at that distance gives footcandles and lux. you can also solve backwards for the candela a target level needs, scale a reading between two distances, convert lumens to candela, and stack overlapping fixtures.
all of it is E = cd/d². tick angled throw and it adds the level landing on a horizontal surface — the cosine loss you feel when a steep backlight reads dim on the floor and fine on a face.
load a manufacturer's .ies file and it pulls center-beam candela and beam and field angle straight from the photometric table, then feeds the other panels. the file is read in your browser; nothing is uploaded.