What is the alcohol content of beer? That's not always an easy one to answer because many breweries don't provide that information. You can figure it out on your own. Meanwhile this is a great conversation starter in brewpubs. Here is a basic formula: ABW = 76.08(OG-FG)/(1.775-OG) or alcohol percentage by weight equals 76.08 times Original Gravity minus Final Gravity divided by 1.775 minus Original Gravity, according to RealBeer. ABW is used mostly in the United States, while the rest of the beer world (as well as the wine and spirits world) measures Alcohol by Volume (ABV). That conversion is easy: ABV = ABW (FG/0.794). You can't find out the alcohol content unless the Original (Starting) Gravity is provided. You may calculate Final Gravity on your own if you have a hydrometer (available in any homebrew store). Just warm the beer to about 60F and pour it back and forth several times to cut down the carbonation. Then use the hydrometer to get a FG reading. Cheers!