How the fermentation sugar calculator works
Yeast turns sugar into alcohol, so the amount of sugar in your must or wort sets the potential alcohol. As a rule of thumb, about 17 grams of sugar per liter raises the finished alcohol by roughly one percent. This tool multiplies that rate by your target ABV and batch size to estimate the sugar to add, plus a rough starting gravity for cross checking with a hydrometer.
Sugar and potential alcohol
Different sugars ferment a little differently, but most simple sugars like table sugar are almost fully fermentable. Honey and some syrups carry a touch more water and trace solids, so you need slightly more to hit the same alcohol, which the sugar source option accounts for. The yeast strain and fermentation conditions also affect how completely the sugar converts.
Specific gravity and OG
Brewers track sugar with a hydrometer rather than weighing it directly. The original gravity, or OG, rises with sugar content, and the drop from OG to final gravity tells you how much alcohol was made. The starting gravity shown here is an estimate; measure your actual OG before pitching yeast and adjust with a little more sugar or water as needed.
Do not over sugar
Every yeast has an alcohol tolerance, often in the low to mid teens for wine yeast and lower for ale yeast. Adding far more sugar than the yeast can ferment leaves a sweet, under attenuated result rather than a stronger drink. Pick a target within your yeast tolerance, and split very high sugar additions across the ferment if you are pushing the limit.
Frequently asked questions
How much sugar per liter for 1% alcohol? Roughly 17 grams of fermentable sugar per liter raises the finished alcohol by about one percent.
How much sugar for 12% ABV? About 200 grams per liter, so roughly 1 kg for a 5 liter batch.
Will more sugar always mean stronger? Only up to your yeast tolerance; beyond that you get sweetness, not more alcohol.
Related calculators: Mead, Beer Priming Sugar, Hydrometer Correction.