The color of beer is measured in Lovibond units or by SRM, Standard Reference Method. The Lovibond method is an objective method where you compare the color of the beer to a chart and pick the closest match. The SRM method is scientific, though the scale was shifted to match Lovibond and they can pretty much be used interchangeably. In both, the higher the number, the darker the color.

For the technical reader, from Wikipedia, the SRM method:

involves the use of spectrophotometry to assign a number of degrees SRM to light intensity. The SRM number is defined as 10 times the absorbance of a sample at 430 nanometers measured through a .5-inch cell. The 430-nanometer wavelength corresponds to a deep blue light, and is the wavelength at which beers appear most different from each other.

Picture your standard megabrewed light American lager (Bud Light) and you will be picturing around a 2. Between 2 and 20 lay a beautiful amber rainbow of colors. Anything higher than 20 is going to be pretty dark, but a porter at about 30 held up to light you will see that it is not completely black. Stouts weigh in at about 35 and higher, up to 70 for something like an Imperial stout.

How much, of which of specialty grains, would one use to make a beer of certain color? I don’t even want to go there, as that is a very complicated subject which has many answers, none of which are perfect. I think the only thing brewers would agree upon is that no one has come up with a method of accurately predicting the color of beer.

For more information on how this scale came about, see this write up derived from Dr. George Fix’s work.

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