How to use the srm beer color calculator
- Choose pounds and gallons or kilograms and liters, and enter the batch size.
- List each grain with its weight and its color rating in degrees Lovibond, printed on the bag or the maltster's data sheet.
- Read the color in SRM and in EBC, the malt color units and an informal color name.
- The table shows how much each grain adds to the total, so you can see what darkens the beer most.
Formula
malt color units MCU = sum of (pounds x Lovibond) / gallons
SRM = 1.4922 x MCU^0.6859 (the Morey equation)
EBC = 1.97 x SRM
Lovibond (approximate) = (SRM + 0.76) / 1.3546
Kilograms are converted to pounds with 2.2046 and liters to gallons with 0.26417. The color names are informal labels for ranges of SRM.
A pale ale with some crystal malt
Nine pounds of pale malt rated 2 Lovibond and 1 pound of crystal malt rated 40, in a 5 gallon batch, give MCU = (9 x 2 + 1 x 40) / 5 = 11.6. The Morey equation gives SRM = 1.4922 x 11.6^0.6859 = 8.0, which is about pale amber, or 15.8 EBC. Pale malt alone, 10 pounds at 2, gives an MCU of 4 and an SRM of 3.86.
In metric, 4.5 kg of pale malt at 2 Lovibond and 0.5 kg of crystal at 40 in a 20 liter batch have an MCU of 12.1 and an SRM of 8.25. The crystal malt is only a tenth of the weight but contributes most of the color, because its rating is twenty times higher.
Why the color is not a straight line
Doubling the malt does not double the color you see. Dark beer absorbs light so strongly that the extra color adds less and less to what the eye sees. That is why the equation uses a power below 1. It is a fit to measurements of real beers, which is why it works best in the middle range and less well for very dark beers.
Limits and uses
The result is an estimate. The malt, the water, the length of the boil and the process all change the final color, and the color names are informal. Brewers use the number to compare recipes and styles and to check a bill of grain for the color they want. Combine it with the Mash Strike Water Calculator to plan the brew day.
More tools for brewing and the lab bench
For related work with brewing and solutions, try the Hemocytometer Cell Count Calculator, Concentration Unit Converter and Mash Strike Water Calculator.
Assumptions and limits
- The Lovibond ratings are the ratings of the actual malt you use.
- The batch size is the volume of the finished beer in the fermenter.
- The Morey equation holds for the beer, which is most accurate for lighter and medium beers.
- The color name is an informal label and not a style rule.
- The grains, weights and batch size in the form are examples to replace with your own.
Frequently asked questions
What is SRM?
It stands for Standard Reference Method, a measure of beer color from light absorbed by a sample. A higher SRM is a darker beer.
What is the difference between SRM and EBC?
Both measure color with different scales. EBC is about 1.97 times the SRM value, so a beer at 10 SRM is about 19.7 EBC.
Where do I find the Lovibond rating of a grain?
It is printed on the bag or the maltster's data sheet. The number varies from one batch to the next, so use the one for your malt.
Why does the page give a Lovibond figure too?
Older recipes and malt sheets use degrees Lovibond for beer color. The figure here is an approximation converted from SRM, which is useful for reading old recipes.