The candela to nano-candela equation converts a measurement of luminous intensity in candela (cd) to units of nano-candela (ncd).
1`n"cd" = 10^-9 * "cd"`
Candela (cd) - the SI unit of luminous intensity. "The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian."1
Additional References:
Check out the Base Fundamental Units Conversion calculator for more light conversions.