With the left button you get a table with vapor temperatures from azeotrope to pure water in 0.1°C or 0.2°F steps and the corresponding %abv calculated in the distillate.
The right button additionally displays the %abv in the boiler. This display is only useful for stills that also have a thermometer in the boiler. Because the temperature at the highest point is usually at least slightly lower than in the boiler. So you can not conclude from the temperature at the highest point to the temperature and thus alcohol strength in the boiler.
The consideration of the atmospheric pressure has a significant influence on the result. If nothing is entered, the calculator assumes the local atmospheric pressure 1013.25 hPa.
Since almost no one has an absolutely accurate thermometer, an additional "thermometer error" can be specified. This can be determined with the help of the calculator Thermometer Error. Temperatures entered or calculated here are then those displayed on this thermometer, not the real ones.

Information about our boiling point data and the influence of atmospheric pressure