Standard Reference Method or SRM is a system modern brewers use to measure color intensity of a beer or malted grain. This is a more sophisticated method involving the use of light meter-analyzers to assign a number of (degrees SRM) to light intensity. The actual SRM number is expressed as 10 times the optical density of a sample at 430 nanometers measured through a 1/2 inch cell. The 430 nanometer wavelength corresponds to a deep blue light, and is the wavelength at which beers appear most different from each other.

Degrees SRM and degrees Lovibond are approximately the same and certainly can be used interchangeably by homebrewers to approximate the color of intensity of their beers.

Color based on Standard Reference Method (SRM)

Budweiser: 2.0 SRM German Pils: 3.0 SRM Yellow/straw/gold

Pilsner Urquell: 4.2 SRM

Bass Pale Ale: 10 SRM Amber

Michelob Dark: 17 SRM Brown

Stout: 35 SRM Black

Imperial Stout: 70 SRM Opaque Black

Brewing