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New Post has been published on http://starthomebrew.com/beer-brew-misc/alcohol-percentage-beer/

Alcohol Percentage in Beer - Weight versus Volume

Some states, like Colorado, require that grocery stores only sell beer that has an alcohol percentage no more than 3.2% by weight. Colorado isn't alone in having this requirement; Kansas, Minnesota, Oklahoma, and Utah only permit general establishments such as supermarket chains and convenience stores to sell "Three Two" beer. In these states, any alcoholic beverages, including beerm containing more than 3.2% alcohol by weight (ABW) must be sold from state-licensed liquor stores.

I remember, shortly after moving to Colorado, I was at a grocery store and getting in line to check-out. In my cart I had a 12 pack of a beer I'd rather not claim to have ever drank. A small old hispanic lady came up to me and said, "Are you going to buy that crappy three-two beer?" This was well before I started brewing beer at home, and I was not only ignorant of how to make my own beer, but I also had no idea what she was talking about. I looked closely at the beer box and realized it seemed to make a point of the alcohol percentage of 3.2. What I didn't know then, but later came to realize, is that the whole 3.2% alcohol by weight (ABW) regulation in some states is a widely misunderstood and pointless regulation.

Why pointless? The answer lies in the way the alcohol content of a beer is expressed. Nearly all alcohol sold in liquor stores and the like has the alcohol percentage stated as Alcohol by Volume (ABV) and not as Alcohol by Weight (ABW). Most people are familiar with ABV since it is the most pervasive way alcohol percentage is expressed. Many people hear about or see the 3.2% ABW beer in a grocery store and simply assume that they can compare this to the beer sold in a nearby liqour store, but ABV and ABW are not equivalent. Here's the surprising part; 3.2% ABW beer is actually equivalent to 4.1% ABV beer (plus or minus 1%). If you're familiar with the ABV of some common beers sold in the United States, such as those listed on the beer list page of this site, you know that most light beers contain around 4.2% ABV. Some have a slightly lower ABV, while others may be slightly higher, but 4% to 4.4% is a very common ABV range for light beers sold in the United States. In short, the 3.2% ABW beer that some people complain about in grocery stores of Colorado is actually the exact same beer that is sold at the liquor store as about 4.1% ABV. ABW is simply not the same as ABV. The perception that the 3.2% ABW beer is lower in alcohol than the same beer sold in a liquor store is just an illusion created by the sneaky use of ABW instead of the most common ABV.

The reason that Alcohol by Volume does not equal Alcohol by Weight is due to the fact that alcohol weighs less than water for any given volume. As an example, consider that a pint of water weighs 1 pound. However, a pint of alcohol weighs only 0.79 pound. This is why a beer with an alcohol content of 3.2 percent by weight is actually 4 percent by volume. A fairly simple way to convert an alcohol-by-weight reading to its alcohol-by-volume equivalent is to multiply the ABW by 1.25. To convert an alcohol-by-volume reading to its alcohol-by-weight equivalent, multiply by 0.80. In case you don't care to do the math, or maybe you've already had one drink too many while reading this, there is a simple chart below showing equivalent alcohol percentage in ABV and ABW.

  Alcohol by

Weight (ABV)

Alcohol by

Volume (ABV)