ClueLuma

Room cavity ratio (RCR) calculator

Room cavity ratio summarizes room geometry for selecting CU with the luminaire distribution and surface reflectances.

Units
RCR=5×h×(L+W)L×W\mathrm{RCR} = \frac{5 \times h \times \left(L + W\right)}{L \times W}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

ft
ft
ft
—

Worked example

Given

  • hh = 8 ft
  • LL = 40 ft
  • WW = 30 ft
RCR=5×8×(40+30)40×30≈2.333\mathrm{RCR} = \frac{5 \times 8 \times \left(40 + 30\right)}{40 \times 30} \approx 2.333

Symbols and units

SymbolMeaningUnit
RCR\mathrm{RCR}room cavity ratio—
hhluminaire-to-work-plane heightft
LLroom lengthft
WWroom widthft

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Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.