D50

D50 is an alphanumeric designation used in several scientific and technical contexts to denote different concepts. The meaning of D50 depends on the field of application, and it is not a single universal standard.

In color science, D50 refers to a standard illuminant used as a reference white point. Defined by the International Commission on Illumination (CIE), D50 has a correlated color temperature around 5000 Kelvin and a specified spectral power distribution. It is widely used in graphic arts, printing, and color management to simulate daylight conditions and provide a consistent basis for color evaluation, profiling, and proofing.

In particle size analysis, D50 denotes the median particle diameter of a distribution. It is the size at which 50 percent of particles by volume or number are smaller. D50 is a key parameter in characterizing powders, emulsions, and suspensions, and it is commonly obtained from methods such as laser diffraction or sieve analysis. It is often reported alongside other metrics like D10 and D90 to describe the spread of the distribution.

Other uses of the term D50 exist in different domains, but the two above are among the most common. Because D50 can refer to distinct concepts, it is important to consider the context to avoid confusion. It should not be confused with related terms such as LD50 (median lethal dose) or ED50 (median effective dose), which have different meanings in toxicology and pharmacology.