Standard Reference Method (Srm) is the method for color assessment of wort or beer as published in the recommended methods of the American Society of Brewing Chemists. See american society of brewing chemists (asbc). It is measured in a cell of path length 0.5 inches (1.27 cm) with light of wavelength 430 nm. The resultant absorbance value is multiplied by 10 to yield the color value and by any dilution factor if the sample needs to be diluted to bring the color within the reliable measurement range of the spectrophotometer. If a 1 cm path length is used (most spectrophotometer cuvettes are such), then the multiplier is 12.7 rather than 10.

In the color method of the European Brewery Convention (EBC), a 1 cm path length is used but the multiplier is 25. Accordingly, EBC color values are approximately twice those on the ASBC scale. A reading is also taken at 700 nm to assess the level of turbidity in the sample, which may be a particular problem for worts. If A700 is less than 0.039 x A430, then the sample is sufficiently bright. If this criterion is not met, then the sample needs to be filtered or centrifuged before repeat analysis.