Quantifying Beer

You may have noticed over in the margin where I've listed the current status of the beers I'm brewing and the planned future brews I aim to make, I have listed stats for each one.  While other brewers will recognize terms like SRM and IBU, not everyone will.  And I'm confident that nobody will know what the "Class" #s mean - mostly because that last part is something I've made up.  So here's a quick rundown of what everything means.

• ABV: Alcohol By Volume.  This is simply a measure of the alcohol percentage of the beer.  The simple kits, those involving only a Hopped Malt Extract (HME) and powdered booster, will all weigh-in at 3.7% ABV.  When you swap booster for an Unhopped Male Extract (UME), you get 4.6% ABV.  Adding other elements like hops or combining booster and UME will also increase the alcohol.  The highest estimated ABV I will be brewing this year is the Christmas Stout which is 6.5%.
• SRM: Standard Reference Method.  This is a measure of the color of the beer.  The lower the number, the lighter the beer.  For those technically inclined, the measurement of SRM involves calculating the attenuation of light of a particular wavelength (430 nm) in passing through 1 cm of the beer.  For comparison purposes, a pale ale has an SRM of 2, Newcastle Brown Ale is a 22, and Guinness is a 40.  Once you get past 40 there's little difference to see - black is black as far as I'm concerned - though Imperial Stouts tip the scales at 70 SRM.
• IBU: International Bitterness Units.  The IBU is based on a scale and measures the perceived bitterness of the beer, which is provided based on the hops used during the brewing process.  The higher the number, the more bitter the beer.
• Class: This is an measure I've invented that combines SRM and IBU into a single number.  The formula is a little complicated, but in rough terms beers with low SRM and IBU will be categorized as a Class 1 beer.  Those with very high SRM and IBU will be Class 6, which is the top end.  Beers in Class 1 and 2 (Blonde Ales, Pilsners, Golden Lagers, Pale Ales and Red Ales made with Booster, and Weizenbier) are light on the palette and aren't expected to be complicated.  Class 3 and 4 beers (Nut Brown Ales, Pale Ales and Red Ales made with UME, Vienna Lagers) are darker and more complicated.  Class 5 and 6 beers (Black Lager, Doppelbock, IPA, Irish Stout, Belgian Dubbel, Imperial Stout) sit up in your glass and bark at you.