There are currently two widely accepted methods of measuring beer color in use in the brewing industry: the Standard Reference Method (SRM), in use in the United States, and the European Brewing Convention method (EBC), used in Britain and Europe. The SRM system relies on comparison to a known standard, while the EBC method measures the absorbtion of light at a wavelength of 430nm by a 1cm deep sample of beer. While the two systems are unrelated, it is possible to convert one to the other using the following formulas to get an approximate value:
1 SRM = 0.375 EBC + 0.46 or 1 EBC = 2.65 SRM - 1.2
The SRM system is based on the older Lovibond scale, which is still used sometimes to describe the color of malt. Basically, one pound of malt at one degree Lovibond will impart 1 SRM unit of color to 1 gallon of beer.
Some examples of these systems applied to commercial brews:
- Budweiser- 2 SRM or 4 EBC
- Bass Pale Ale- 10 SRM or 25 EBC
- Guiness Extra Stout- 50 SRM or 130 EBC