In our recipes on the web shop, you can see in advance how much alcohol there will be in the beer. You can trust this blindly, but it is of course much more fun to check yourself whether you also achieve this alcohol percentage or perhaps more or less. By calculating the alcohol percentage in each brew, you can also recognise mistakes that you will change during the next brew day and thus make yourself better. 

You calculate the alcohol content from sugar that has fermented. Your wort contains a certain amount of sugar before fermentation. By measuring the amount of sugar after fermentation, you can use a formula to calculate how much sugar has been converted into alcohol and thus your alcohol percentage. We measure the sugar content with a hydrometer. This instrument measures the density of a liquid, in our case wort. We then use this formula to calculate the alcohol percentage:

Start SG - end SG x 0.136 + 0.3 = Alcohol percentage

This formula uses a number of parameters, namely:

Initial SG: This means the sugar content of your wort before the yeast has done its work. You always measure the begin SG on the day of brewing. SG stands for 'specific gravity'.
Final SG: This means the sugar content of your beer after the yeast has done its work. The end SG is therefore always measured after the secondary fermentation/lagery of your beer.
0.136: This is an average value for all beer styles. It is a conversion factor in which a number of things are taken into account such as: aeration, amount of formed yeast, the protein percentage in the wort and the fermentation temperature.

To calculate the alcohol percentage you need the following items, which can also be found in our webshop:


You want to measure the starting SG and you do this after brewing the beer. First make sure the wort is cooled down to 20 degrees, at higher temperatures the hydrometer does not work properly. 

Fill the measuring beaker with at least 100 millilitres of wort. Then carefully lower the hydrometer into it. 

In the example, you can see that the starting SG is 1058.

Do not throw the wort back into the fermentation bucket, you want to avoid the chance of contamination as much as possible.


You want to measure the final SG after the fermentation of the beer. 

Again, fill the measuring beaker with 100 millilitres of beer and carefully lower the hydrometer into it.

In the example, the final SG is 1024.

You do not throw this beer back into the fermentation bucket either. But you can already taste this beer so you have an idea how it will taste. This will not be the final result as the taste will change quite a bit during the refermentation.


With the data from steps 1 and 2, you can calculate the alcohol percentage. Use the formula: 

Start SG - end SG x 0.136 + 0.3 = Alcohol percentage

The initial SG in this example is: 1058
The final SG in this example is: 1024
Formula: 1058 - 1024 x 0,136 + 0,3 = 4,9%

Have fun and good luck with brewing!