The exact color of beer is not of great concern if you are simply going to enjoy the process of making beer and drinking it. However, if you are fine-tuning your skills as a brewer and/or trying to match a beer or attempting to win in competitions, you may wish to consider measuring your beer color.
The color of beer is influenced by several factors during the brewing, fermenting and handling process. Malt usually has the most significant impact on the color of beer; a discussion of malt and its effect on color is found in Malt.
There are two standard color measurements used by professional brewers. One is the American Standard Reference Method (SRM, nearly identical to the older degrees Lovibond system), and the other is the European Brewing Convention (EBC). Each uses different analytical procedures. It should be noted that each system has its limitations and does not actually measure the color, but rather the intensity of certain types of light. The systems do not recognize the difference between a coppery red beer, an amber, a gold, yellow, or shades of redless brown.
There is not a dependably calculable relationship between EBC and SRM color units. However, the following relationship is reasonably accurate for gold- or straw-colored beers of about 4 degrees SRM or less. For colors darker than 4 degrees SRM, the relationship is an undependable and unscientific estimate, but something is better than nothing.
degrees EBC = (2.65 × degrees SRM) - 1.2
or
degrees SRM = (0.377 × degrees EBC) + 0.45
The equipment necessary to analyze color using standard methods is far from the means of even the above-average homebrewer. But a simple method of color analysis for beers whose color is less than or equal to 17 degrees SRM has been developed by Roger Briess and George Fix. Their method is outlined here with their permission.
The standard for the method is Michelob Classic Dark, brewed by Anheuser-Busch. It is generally widely available and its color is consistently 17 degrees SRM. The method is quite simple and compares the color of carefully measured dilutions of Michelob Dark to the beer being evaluated. The amount of distilled water it takes to dilute Michelob Dark to appear equal in color to the evaluated beer correlates to the color of beer in degrees SRM.
Color Intensity (° Lovibond)
The authors of this method recommend that distilled water be used as the diluent. Both the Michelob standard and the test beer should be degassed by agitation because dissolved carbon dioxide can affect color. Reflected indirect light sources should be identical when observing samples.
Clear “white” glass long-necks are convenient vessels to use for making comparisons. Syringes or pipettes should be used to accurately measure volumes of liquid. For reference note that 1 cup = 8 fl. oz. = 237 ml., and 12 fl. oz. = 355 ml.
To make the evaluation, begin with 20 milliliters of degassed Michelob Dark. Add distilled water to the Michelob until it matches the color of the degassed sample. Refer to the chart to determine the color rating of the sample.