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This month's question:  How do I calculate the color of my beer?

Answer:  This turns our to be a fairly straight-forward task.  Color of finished beer is expressed in units known as SRM, which stands for Standard Research Method.  Color can be calculated if you know the amounts and color of your malts, your extract efficiency and your extent of boiling. 

Malt color comes in units known as Lovibond, abbreviated oL.  Usually, the color of the malt is listed on the container.  When you're buying malts, make sure you note the Lovibond for each grain.  The first step in the color calculation is to multiply the pounds of grain by its Lovibond color.  Then add up all the parts and divide by the batch volume. Fianlly, multiply by a conversion factor of 0.46.

Let's take the following recipe for 5 gallons of Amber ale as an example:

Pale Ale Malt        3oL  8 pounds

Crystal Malt        60oL   1 pound

Chocolate Malt  350oL   2 ounces

Pale malt contributes           3 x 8 = 24 color units

Crystal contributes             60 x 1 = 60 color units

Chocolate contributes 2/16 x 350 = 44 color units

Total Color units:                         128

Then, divide by the batch size, and multiply by the color factor 0.46:   128/5x 0.46= 11.8

Note the huge contribution from just a small amount of chocolate malt.  Keep this fact in mind when you formulate recipes. 

Next, you have to correct the color by your extract efficiency.  If you're an extract brewer, use 100%.  If you're an all-grain brewer, this is your actual point-pounds per gallon divided by the theoretical point-pounds per gallon.  With my setup, I get about 76%. 

Hence, in this example, I get 11.8 x .76 = 9.0

Now, if you didn't boil the wort, you'd be done.  However, the wort darkens as it boils.  Typically, this will darken the color by 25% or so, depending on the heat and the length of the boil.  Long hard boils will yield darker color.  Hence, the final color will be:

9.0 x 1.25 = 11.2 SRM.

One way to simplify this procedure is to note that the extract efficiency and the boiling just about offset each other.  You could ignore these factors without a huge effect on your estimate.

Sometimes, the colors of some of the malts aren't listed.  Ask your friendly neighborhood brewshop owner.  He'll probably know.  If not, use the table below.

Malt Type

Color, Lovibond

Malt Extract (Light*)

7

Pilsner Malt

1.6

Pale Ale Malt

3.0

Chocolate Malt

350

Black Patent

525

* Liquid or Dry.  Note, however, that liquid extracts will darken with age.

Finally, if you're brewing for competition, you should try to hit the proper color for style.  Following is table of style colors, according to the BJCP.  In the example above, you'll note that the color of the Amber is 11.2, whereas the table below suggests less than 11 to 18.  You could add a another ounce of chocolate malt to bring up the color by2.1 points.  Don't get too hung up on this though.  Color only counts for one point out of 50.  It's much more important for the flavor to be true to style.

Beer Style

Color, SRM

Pilsner

3-6

Pale Ale

6-14

Amber Ale

11-18

Brown Ale

12-30

Porter

Over 30

Stout

Over 35