Thomas wrote:In the USA, up to 14% a wine has 1 to 1.5% leeway, plus or minus. So, the answer to your question is: you never really get to know the alcohol level.
I'd just like to point out that the rules in the US are complicated and it all has to do with taxes. The tolerance for wines under 14% is +/- 1.5%, the tolerance for wines 14% and over is +/- 1%, which I always thought was odd (why a bigger tolerance for lower alcohol?). 14% represents the breakpoint between tax categories. The extra complexity is that despite those general tolerances, the label *must* agree with the tax category. In other words, if the label shows a number less than 14%, the actual alcohol must be less than 14%. So if, for example, the label says "13.9%", the actual alcohol could be anywhere from 12.4% to 13.999% - but not 14.0% or greater. If the label says 14.1%, the actual alcohol could be anywhere from 14.0% to 15.1%. These rules are the reason why in the old days so many wines were labeled at 12.5%. Especially for the nonvintage wines that used to be prevalent in California, a winery could use the same label for wine anywhere from 11% to 14% alcohol, year-in and year-out, more or less forever.