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What Is SRM in Beer?

Article Highlights

  • SRM stands for Standard Reference Method and is an expression of the color of a beer before it is carbonated and other additions are made
  • It is measured using a spectrophotometer which counts light absorbance as it passes through a standard recess or goes around the sample being tested
  • SRM gives an indication of beer color based on light absorbance at specific wavelengths
  • Factors that affect SRM values include the grains used, mash temperature, length/temperature mash rest, water quality/pH levels, yeast strains/flocculation habits, filtration level and carbonation level
  •  Brewers use SRM to monitor quality in brewing by making data-driven decisions and adjusting processes if needed to minimize any potential flaws before releasing into the market

This blog post explores what SRM is, how it’s measured and calculated, its relationship to color, the factors that affect its values in beer, and how brewers use it to monitor quality.

SRM stands for Standard Reference Method. It’s an expression of the color of a beer before carbonation and other additions are made.

It’s measured using a spectrophotometer which counts light absorbance as its passes through a standard recess or goes around the sample being tested.

Color is then expressed in terms of degrees Lovibond or Standard Reference Method (SRM).

What Is SRM in Beer?

SRM is an indication of beer color that takes into account light absorbance at specific wavelengths when the beer passes through a polarimeter. The value expresses the amount of malt color present in the uncarbonated beer from dark black to nearly a straw yellow color.

The higher the number on the scale of 1-40+, the darker the brew. A glass of blonde ale will be somewhere around 4-6 on this scale while a porter could range up to 20+.

How SRM is Measured and Calculated?

The Standard Reference Method (SRM) was developed to define and measure color levels in beers brewed with light-colored grains such as wheat, barley, and oats which can tend to show a huge variation in the shade when viewed under different lighting conditions.

The method used today matches a specific wavelength (430nm) against a reference glass with known absorbancy properties at that wavelength (called ‘Standard Reference Material’ or ‘SRM’). The resulting calculation establishes the color value for that sample of beer and expresses it using “degrees Lovibond” or “SRM”.

Relationship Between SRM and Color

As we discussed above, SRMs are based on light absorbance at specific wavelengths which helps us calculate degrees Lovibond for each sample tested. But what does this actually tell us about color?

Generally speaking, higher numbers on the scale mean darker colors like those found in Porters with high malts while lower numbers equate lighter colors like those seen in Wheat beers and Blonde Ales with fewer malts used during production.

This makes sense since more malt means more color depth – hence why some styles contain more malt than others!

Factors That Affect SRM Values in Beer

There are quite a few factors that can influence your final results when reading an SRM meter:

  • Grains used: Different grains will produce different levels of maltiness depending on their makeup which affects SRMs;
  • Mash temperature: When mashing grains this can change results due to how enzymes break down starches within them;
  • Length/Temperature Mash Rest: How long your grains are left to rest during mashing can affect absorption rates;
  • Water Quality & pH: Certain water characteristics may enhance flavor but also change results;
  • Yeast Strains/Flocculation Habits: Different yeasts will flocculate at varying rates; &nb sp;
  • Filtration Level & Carbonation Level: Both carbonation levels (if bottle conditioning) and filtration levels impact SRMs too!

Use Of SRM To Monitor Quality In Brewing

Brewers use Standard Reference Methods for data-driven decisions about their beers. This helps ensure consistency across batches by providing them with objective data points they can compare against each other.

They can also use this information to adjust processes such as mash temperature or water balance if they need to fine-tune certain aspects like bitterness or clarity after tasting samples against prior batches brewed under similar conditions!

Furthermore, they can also use SRMs alongside traditional tastings when judging competitions since it provides another layer of feedback beyond subjective tasting notes alone – allowing both amateur brewers as well professional brewers alike to weed out potential flaws early on before packaging their products commercially!


Standard Reference Method is an essential tool for breweries looking to achieve consistent results across batches while monitoring quality during production by evaluating both subjective tastings alongside objective measurements such as those provided by an SRMs spectrophotometer device.

Furthermore, brewers may adjust processes if needed depending on what readings come back from their samples allowing them to minimize any potential flaws before releasing them into the market – making it one invaluable piece of equipment every brewer should own!

Author Image Fabian
I’m Fabian, homebrewer and beer taster. I’m also the editor of Beer100. I love travelling the world and trying out new handcraft beer and different beer styles. I’m not an expert in brewing beer, but I know a few things about beer, which I share on this blog. If you need help or have a question, please comment below.

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