First enter the volume and %abv of the still contents before the first distillation. Optionally enter the local atmospheric pressure and the thermometer error.
Then up to four distillation sections and the stillage (the boiler content after distillation) are calculated. For example with meanings like foreshots, heads, hearts and tails. For this, one enters the end of each section. For example, "until 60%abv current distillate".
For each section you can enter an individual number of theoretical plates. So, for example, for a slow foreshots separation, a higher number than for the hearts. "1" means a theoretical potstill without any rectification. "2" means an additional distillation, quasi a double distillation in a single distillation process. One can (and should in a potstill distillation) also enter decimal values. Because a normal potstill has about 1.1 - 1.3 theoretical plates depending on the construction (for example lid insulation and riser length). But of course you can also enter higher values (reflux distillation).
After pressing "Calculate" the distillation is calculated in up to 300000 small steps. This can take a few seconds. Especially if distillations with many theoretical plates are calculated.
In the table below, percentages are given. To the left of the name of the substance are the percentages of the substance in the still before distillation. That is 100% everywhere at the first distillation. And then next to it, how these percentages are distributed among the individual sections and the stillage.
If you move the cursor over an congeners name without pressing, alternative names and further information about this substance are displayed.
Now you can either repeat the distillation or continue.
To repeat, simply change the entries in the sections and then press "Repeat distillation".
If you want to continue, you can now select sections (check the box below the section) and optionally add water. You can now either put this new mixture back into the still to distill it again, or you can use it to calculate the final result.
If you want to distill again, you have to press "Selection into the boiler". Then the volume and %abv of the mixture are entered at the top and in the lower table to the left of the substance names the percentages which are still left, i.e. have not been discarded. Then choose again the ends of the sections and their theoretical plates and calculate again.
If you want to have the final result, you have to press "Calculate final result". Then the most important values of the performed distillations are shown again and the percentages of the congeners are listed.
The order of the congeners within their group (for example "Esters") depends on their molar mass. In general terms, the larger molecules within a group of congeners are those with the better aroma or those from which the more interesting aromas can be created.
There are the absolute values: This shows how much of the congeners are left compared to before the first distillation. This is between 0 and 100%. 0% means a congener has been completely separated. 100% means, a congener has completely ended up in the final result.
The values relative to ethanol have more meaning in practice: If the value is above 100%, the substance has a higher presence than before the first distillation. At 200% it is twice as present, at 50% half as present. Whereby double presence does not mean double flavor strength. Our senses generally need far more than double the stimulus to feel double. The higher these percentages, the more flavor the distillate has.
Then, depending on the group, there are values relative to a congener. This allows conclusions to be drawn about the quality of the aroma.
Contraction is taken into account in all calculations.
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.

More information about congeners and calculation examples
Information about our boiling point data and about the influence of atmospheric pressure