Beer spans an endless array of colors. The deep black color and white foam of an Irish Stout, deep copper of a Pale Ale and cloudy light color of a Bavarian Wheat are all within the rainbow we call beer. Today we’ll look at beer color, how its measured, color limitations, and how to estimate the color of a beer recipe.
The History of Beer Color
The system used to characterize beer color has its origins in the late 1800’s. The original lovibond system was created by J.W. Lovibond in 1883, and used colored slides that were compared to the beer color to determine approximate value. For decades, beer was compared to colored glass standards to determine the Lovibond color, and we still use the term “Degrees Lovibond” extensively today to describe the color of grains.
Over time, limitations of the Lovibond were recognized, not the least of which was that it depended upon a person’s vision – which naturally has variations in color perception from person to person. By the mid-20’th century, light spectrophotometer technology was developed. In 1950 the ASBC adopted the Standard Reference Method (SRM) color system. Separately the Europeans developed another visual system called the European Brewing Convention (EBC). It originally used visual comparison, but some 25 years later changed to use a spectrophotometer in a slightly different way than SRM.
Measuring Beer Color
The SRM color of beer is measured using a ½” glass cuvette measured by a spectrophotometer at a light wavelength of 430nm. The SRM color is approximately 10 times the amount of absorbance, which is measured on a logarithmic scale. The SRM color is approximately equal to the old lovibond scale in most cases. The other common method, called the European Brewing Convention (EBC) is measured at the same wavelength but in a smaller 1 cm cuvette. In practice the EBC color is approximately 1.97 times the SRM color. (EBC = 1.97 * SRM) [Ref: Daniels]
If you don’t have a spectrophotometer handy in your personal laboratory, a number of tools are available to help you measure the color of your beer. The most popular and easy to use is a beer reference color card, such as the Davidson guide, to do a visual comparison of your beer against standard reference colors. I recommend purchasing such a guide from your local store. I don’t recommend printing an online color card, as the variations in printer color will spoil your measurements.
Another method involves diluting your beer with distilled water and comparing it to known color standards such as mass produced commercial beer. Ray Daniels describes this method in detail in his chapter on beer color from his book Designing Great Beers, if you are a truly dedicated brewer. For my money, a nice beer color card is easier to use.
Estimating Beer Color for a Recipe
As a home brewer, I’m very interested in how to estimate the color of my beer for a given recipe in advance of brewing. In practice, good home brewing software like BeerSmith will automatically estimate the color of your recipe as you build it, but I think it is still useful to know what is going on under the hood.
A first iteration at estimating beer color involved simply calculating the Malt Color Units (MCUs) of a recipe.
- MCU = (Weight of grain in lbs) * (Color of grain in degrees lovibond) / (volume in gallons)
For multiple grain additions, you can simply calculate the MCU for each addition and add them together. MCU provides a good estimate of SRM color for light beers, but starts to diverge as beer color exceeds 6-8 SRM, because light absorbance is logarithmic and not linear. For a more accurate estimate that holds for darker beers up to about 50 SRM, we turn to the Morey equation:
- SRM color = 1.4922 * (MCU ** 0.6859)
The Morey equation provides an excellent estimate of beer color throughout the range from 1-50 SRM, and is the one used by most brewers today.
Limitations of Beer Color and Color Estimates
No matter how accurately your color estimate or measurement is, you need to recognize that all existing beer color systems have very real limitations. The SRM color system, for instance, is measured from the absorbance of a single wavelength of light. It can’t tell the difference between similarly colored red beers and amber beer, for example. The subtle hues of red and brown may look identical at the 430nm wavelength.
In fact, it is not possible to specify the precise color of a beer with a single “beer darkness number” such as SRM. The subtle variations in red, brown, gold, copper and straw can’t be captured in a single dimension beer color system. Irish Red is a good example – if you do an estimate of the color for an Irish Red you will likely get something that does not look very red at all on the color card. Yet the addition of a tiny amount of roasted barley gives it the distinctive red hue that the SRM system simply can’t capture.
Extract brewers need to be aware that liquid extracts in particular tend to get darker as they age, and also that extracts will darken in a process called carmelization as they boil. I wrote an article on how to use late extract additions to reduce this effect. The net result of the aging and boiling effect is that many extract beers come out substantially darker than an estimate would indicate.
In practice, these issues are not a problem for the average home brewer, but commercial breweries often use coloring agents, mixing of batches and other techniques to achieve very precise color matching from batch to batch. For a home brewer, it is enough to know that a color estimate has limitations.
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Great article, especially the tip on getting an Irish Red to look, well, red.
Thanks John,
Red beer is usually regular ale with just a touch of roast malt – as little as 1-2 ounces.
I saw that you have a logorithmic formula for determining the color of a beer. How about one for determining the ph of a beer. It could help to find which beer would taste more bitter than others.
Hi Russel,
Ph is a function of a number of variables, most importantly water composition and the grains used. If you do a quick search, I recently published a separate article on beer Ph.
Hi,
Dear Sir,
May I know which factor is the main factor for the color of a beer?
And can you kindly give me some helps for brewing a good standard beer?
Thank you very much,
Sincerely,
Zaw
Zaw,
The main factor in the color of the beer is the color of the malts you choose to include in the beer. Darker color specialty malts result in darker beer. You can get some good starting point recipes by visiting our forum or recipe page. The forum link is listed a the top of this page and the recipe archive is in our links to the left.
I prefer St. Rogue Red http://bit.ly/3vAUy1
I find myself second guessing this. Here is an example. I have a malt that is 50-70 ASBC. If I use the conversion on beercolor.com I get 100-140 EBC. Converting EBC to SRM and Lovibond, I get the following.
38.1-53.2 SRM
60.6-84.8 Lovibond
So, which numbers do I plug into BeerSmith, the SRM or Lovibond rating of the grain?
Thanks,
don
I would go with the lovibond rating.
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You’re all at the wrong wavelength. You’re trying to determine color when you should be looking at shade. 780 nM would work way better.
Matt, I believe the wavelengths I quoted are the ones defined by the standards – not ones I selected. I agree other wavelengths could be used, but for now the SRM and EBC standards specify the listed wavelengths.
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Hi,
The article about estimating beer colour is very informative. However, as I live in the UK and I mainly use the metric system, as well as EBC, I was wondering if there is any formula to work out beer colour without converting the values from the Imperial System (American) and SRM to metric and EBC and vice versa. That would make my life very easy.
Also, will the Morey equation be applicable?
EBC=1.97 * SRM (or it is roughly double the color of SRM).
Unfortunately, I only see ingredient colors as SRM or the optional EBC, forcing me to calculate L (and requiring conversion of supplier given L for entry into ingredient list) . When looking up ingredients I wish I could use Lovibond because my supplier uses that instead of SRM. Seems you could easily let user select that as a default FOR VIEWING INGREDIENTS.
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I noticed that the conversion formula is for SRM to EBC. Cooper’s extract cans are listed as EBC. I started using them in partial mash recipes just to apply my newfound PM brewing skills to the extract cans I used in my AE brews.
I found a lot of controversy surrounding converting from old to new,& came up with a formula to convert EBC on the Cooper’s cans to SRM you use in Beersmith. It’s (EBC/1.97) x 1.97 = SRM. Or as an example,the Cooper’s Heritage Lager can lists color as 90EBC. So (90/1.97)=45.69 (rounded off) x 1.97 – 90.0093. I assumed Cooper’s rounded this off to the nearest whole number. I hope this helps when folks are adding ingredients to the “grains” list.
Just realized that doesn’t seem right. Oops. More like 45.69 would be SRM. My bad. My heads swimmin trying to get BS numbers right.
Can Lovibond colour measurements be made on simple UV/Vis Spectrophotometers?
Very useful formula. I live in the UK so mainly use the imperial system. The weight in lbs of course is fine, however over here we use imperial gallons. I guess a little tweak to the formula should put it right for us on this side of the pond!
“Extract brewers need to be aware that liquid extracts in particular tend to get darker as they age…” Is this referring to in the bottle aging or if I have some liquid extract sitting around on my shelf or pick some up from a garage sale and have no idea how old it is, that using it in a recipe will yield a darker beer as a result?
HELP! I’m going crazy! I am trying to measure the SRM of my malt extract and bought a spectrophotometer. At 430 nM A = 1.13. If I’m doing this correctly, this would make the SRM between 11.3 and 13.97 depending on which multiplier is used. Here’s the catch- when I compare my 2″ sample to a beer color card it looks to be around a 2. Am I doing the math wrong or is the spectrophotometer a DUD?
SRM is defined as 10 times the absorption in 1/2 inch and EBC 25 times the absorption in 1 cm at 430 nm. If absorption is measured in 1 cm cuvettes as it almost always is today, EBC is simply 25 times the absorption and as there are 12.7 mm in half an inch SRM is 12.7 times the absorption in 1 cm. These are exact definitions. In the example where A = 1.13, assuming a 1 cm path, SRM is 12.7*1.13 = 14.35 and EBC is 25*1.13 = 28.25.
There is no 1:1 mapping between SRM and visible color. One must also take into account the length of the path through the beer that the light must take in reaching the eye and the nature of the light source. The beer at the top of the classic conical pilsner glass looks much darker and redder than the beer at the bottom near the stem.
Given that you know the color depth, the product of the SRM and the length of the path L you can get an amazingly good prediction of visible color of the beer. As color depth gets above say 100 SRM-cm the color becomes more saturated than the gamut of CRT’s and printing processes. Many of the available guides show colors which are not even close to actual beer colors.
It is true that the subtler color differences cannot be modeled by a single number (SRM). But they can be modeled very well using two to four additional parameters which I call spectral deviation coefficients. SDC’s are calculated from the spectral absorptions at 81 wavelengths starting at 380 nm and progressing up to 780 nm in 5 nm steps.
Hi, I was wondering if anyone had any luck finding or locating some SRM color standards that they can use to verify beer color? EBC standards would also work since there is a simple conversion, but I am having trouble finding either. Has anyone had any better luck?
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Hi Brad, great article. I am in the UK and read that the ebc colors changed around 1990. I was wondering if there is a formula for converting old EBC (pre 1990) to new EBC. A lot of the older brewing books (Graham Wheelers) seem to use the old measure. Thanks. Dave…
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Why do the grain ingredients for most entries have the Lovibond value entered for the SRM? Should be able to set what units are used. This really needs to be corrected and fixed.