Calculate the capacity of a boiler or keg from its dimensions, a safe charge, sugar and water for the wash and the expected distillate from one run.
How much sugar fits in the boiler?
The calculator gives the sugar and water for the chosen gravity so that the finished wash fills the boiler to a safe level. If you ferment in a separate vessel, remember that the wash volume hardly changes during fermentation.
How full should a still boiler be?
Leave at least 15–20% free space. A boiling wash foams, and foam carried into the column fouls the packing and spoils the taste. Leave even more room for fruit and grain washes.
How do I calculate capacity from dimensions?
Measure the inner diameter and height of the boiler and the calculator works out the cylinder volume. For a keg with a domed bottom the result is slightly low, which gives an extra safety margin.
How we calculate
Cylinder volume V = π × (d/2)² × h. The safe charge is capacity × fill %. Sugar is derived from the density of a solution of the chosen gravity.
Frequently asked questions
How full should a still boiler be?
Usually up to 75–80% of its capacity. The wash may foam, and foam carried into the column spoils the distillate.
Is a beer keg suitable as a still boiler?
Yes, 30 and 50 l stainless kegs are very popular. Before converting it, release all pressure from the keg, remove the valve (spear) and clean the inside thoroughly.
How do I measure a keg's capacity without dimensions?
Pour in water with a jug or bucket of known volume up to the level you want to fill – the most accurate method, because it includes the domed bottom and rims.
Which boiler should I choose for my still?
For home distilling 30–50 l stainless steel boilers and kegs are the most popular. A bigger boiler means fewer runs but longer heat-up.