get FermentCalc

Backsweetening Calculator

Enter the batch size, its current gravity and the gravity you want, pick a sweetener, and get the exact amount to add - plus the carbonation risk if it ever re-ferments.

L

The volume of finished, stabilized cider or mead you are sweetening.

SG

A hydrometer reading of the batch right before sweetening, corrected for temperature.

SG

Around 1.005 is barely off-dry, 1.010 is medium and 1.015 and up reads clearly sweet. Sweetness perception also rises with acidity and tannin.

Results

Sweetener to add
739g
Per liter of batch
38.9 g/L
Potential CO2 if fully fermented
7.8 volumes of CO2

Stabilize before backsweetening still meads and ciders: potassium sorbate plus Campden (metabisulfite) together keep the yeast from re-fermenting the new sugar. Unstabilized, the potential CO2 figure above is bottle-bomb territory.

How the backsweetening math works

The gravity gap in points times the batch liters times 2.61 gives the grams of sucrose needed; each sweetener divides that by its sugar fraction - honey about 80.5%, table sugar 100%, fresh apple juice about 12%. The CO2 line applies the rough rule that about 4 g of fermentable sugar per liter produces one volume of CO2, so it shows what would carbonate - or burst - if the sweetener ferments out.

sugar (g) = (target - current) x 1000 x L x 2.61; sweetener (g) = sugar / fraction; CO2 volumes = sugar / L / 4

Planning the batch from scratch? The mead must calculator sizes the honey up front, and the cider ABV calculator confirms where the ferment actually finished before you sweeten it.

Frequently asked questions

Why stabilize before backsweetening?

Potassium sorbate stops yeast from reproducing and metabisulfite knocks the population back; together they let the sweetener sit in the batch unfermented. Sorbate alone does not kill yeast, and neither works in an actively fermenting batch - wait until the hydrometer has been stable for days.

Which sweetener should I use?

Honey re-adds mead character and aroma, table sugar is neutral and easiest to measure, and fresh apple juice is the traditional cider route, diluting while it sweetens. Juice needs the most volume by far - at 12% sugar it takes roughly eight times the weight of sugar for the same gravity lift.

How sweet should I aim for?

Start low: move the gravity to 1.005-1.010, stir, taste on the next day, and step up if needed. Acidity, tannin and serving temperature all push perceived sweetness around, and a batch that tastes balanced at 1.010 can taste cloying at 1.020.