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How is alcohol strength in beer measured?

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Six small glasses of craft beer in varying amber and golden hues are arranged on a metal tray atop a wooden bar counter in Brussels, Belgium. — Beer Glasses of beer in a bar in Brussels.

The alcohol strength of beer is primarily measured by the percentage of ethyl alcohol by volume, commonly referred to as alcohol by volume (ABV).12

This measurement indicates the concentration of alcohol within the beverage. While standard beers typically contain lower percentages, stronger varieties—such as those categorized as barley wines—can reach 8 to 10 percent ABV.12

To determine the characteristics of liquids during production, brewers may utilize a hydrometer, a device that measures density or specific gravity. While hydrometers can be calibrated for various purposes, including measuring sugar content or the "proof" of an alcohol solution, the final strength of the finished beer is expressed as a percentage by volume.312

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