How to measure the alcohol level of home beer Want to know how many percent alcohol your beer has, but the alcohol meter does not show reliable results? Read this short text and everything becomes clear.

Many budding home brewers want to know its power after brewing their first beer. However, in order to reliably assess the level of alcohol in home beer, we must start measuring at the stage of brewing the beer, and more precisely before fermentation begins. The use of popular alcohol indicators will not give us reliable results in this case. Floating alcohol meters work like hydrometers, i.e. they indicate the density of a liquid through the depth of its immersion. This is the so-called hydrometric measurement. Since ethanol has a lower density than pure water, its presence in water will reduce its density. Therefore, the higher the level of alcohol in the solution, the deeper the floating alcohol meter is immersed.
For mixtures other than pure water and ethanol, the level of density will be influenced by various substances, including sugars. For this reason, it is not possible to measure the alcohol level in beer, wine or other colored alcohols using the hydrometric method.

So how do you measure the alcohol level in your home beer? By measuring the amount of fermented sugar. It is assumed that in order to obtain 1% alcohol, 17g of sugar / 1l must be fermented. However, this process is not completely linear, so various equations are used to approximate the amount of alcohol. It must be remembered that the key issue in using such formulas are the units in which we measure the sugar level. Polish brewers most often use BLG as the units of sugar density in wort.

So let's move on to practice.
We measure the sugar level in the wort with a hydrometer before fermentation. Remember that its temperature must be 20 ° C - this is how the hydrometric indicators of density are calibrated, this applies to both alcoholometers and sugar meters. The sugar measurement shows us an example value of 14BLG. We make another measurement after the fermentation is finished, before the beer is bottled. Suppose the hydrometer reads 2BLG. These two parameters are the most important for us to calculate alcohol using the formula below


(BLG Initial - BLG Final): 1.938 =% abv (vol)

So for our parameters the result looks like this

(14-2): 1.938 = 6.2%

The given result is of course an approximation, but it applies to slight differences after the decimal point. It allows for a fairly accurate assessment of the strength of our beer. Be precise, remember that adding sugar to refermentation will raise the alcohol level by about 0.3-0.4%.