I'm a home brewer and I'm trying to figure out the most accurate way to measure alcohol. Is a hydrometer or refractometer more accurate? If I use a refractometer, how do I convert that to the actual alcohol percentage?
A refractometer will only measure sugar accurately, once you beer ferments you need to use a hydrometer. Best to get a as good a hydrometer as you can, preferably one with temperature adjustments. For the easiest way to get a close estimate of alcohol content you need to convert your Original Gravity and Final Gravity to Degrees Plato, this is easily done just divide the last two digits by 4, for example 1.048 is 12 Degrees Plato. Once you have these two numbers converted you can estimate alcohol as % by weight :
(Original Gravity – Final Gravity) x 0.46
You can convert % ABW to Alcohol by Volume by dividing ABW by 0.789.
That’s your beer math lesson for today, hope it helps your brewing!