Specific Gravity, Brix, & Plato Conversion Calculators

by Karl | Last Updated: May 11, 2020

We all have studied the process of alcoholic fermentation in our high school chemistry classes. Just to refresh your memory, fermentation is simply the conversion of sugars, be it glucose, sucrose, or fructose, into alcohol and carbon dioxide. 

Simply put: no sugar = no alcohol.

The primary content of beer is its alcohol content, and there is so much that can change due to a minute change in its alcohol content. It’s what makes up a the taste of the drink or even its gravity, as we will take a look at below.

If you are a brewer, you need to look at establishing the alcohol contents of your brew. For it, there are a set of calculations that you need to do first. These calculations are an integral part of the beer brewing process and determine the decision and -process being done in the breweries.

What is Specific Gravity?

The specific gravity of any liquid is referred to its density when compared to water. Now, in the case of beer, various factors attributed to the thickness of a brew. Your beer has traces of sugar, starches, hops, malts, oil, and minerals. 

Many brewers measure this specific gravity of the beer before beginning the fermentation process. They also do it after the culmination of the fermentation process. These brewers, then make use of this data and some calculating algorithms and formulae to calculate the alcohol by volume of every batch.

What is Brix?

A Brix value is expressed in degrees Brix. (°Bx) and defined as the amount of sucrose in grams present in every 100 grams of liquid. 

The value of this parameter can range from 1 to 100 and is useful in the calculation of approximate alcohol content by simply multiplying it by 0.59. 

For instance, if a pre-fermented liquid measures 10 Bx, its potential alcohol content would be 5.9. 

However, one must note that this is just an approximate value, and other factors like temperature and process are not incorporated in the calculation. 

How do you measure it?

Now, we know what Brix is and hot it enables us to estimate the potential alcohol content in a beer blend. To measure Brix, we use two instruments namely –

Refractometer: A refractometer makes use of the refraction of light passing through a particular liquid sample. Liquids that contain sugar are denser than water, and in accordance with the snell’s low – density is directly proportional to the increase of refraction. This instrument then compares this refraction to provide a Brix value. 

Hydrometers: A hydrometer is used both before and after the brewing process. It makes use of the liquids’ relative density to calculate the sugar content. 

Many brewers, though opt for the technique involving refractometers to calculate the Brix of a sample. This is simply because a refractometer is much more convenience than a hydrometer, 

The refractometer measures the levels of potential alcohol when alcohol is present. This makes the refractometer an ideal tool to determine the Original Gravity of the brew. Even though the calculations involving these factors will get you close to the correct potential alcool value, there is a lot of conjecture about their precision.

In situations like these, where this calculation can be critical, one should always go for a hydrometer, right after the fermentation process kicks off.

With that said, while calculating the Brix value, it is essential to consider temperature to ensure precise values.

Why do we measure Brix?

The calculation and estimation of the alcoholic strength of a brew are of great interest to all brewers.

Beer brewers need to take down the values and data before, after, and during the fermentation process. This data then further allows them to monitor factors like the progress of fermentation, mash efficiency, and the results of each recipe. 

Similar to brewers, a lot of winemakers also calculate the Brix value for calculation of the potential alcoholic strength. This value helps them evaluates and study the time when grapes ripen or sugar levels increase. 

For winemakers, knowing the Brix value is important. It’s what helps them know how ripened the grapes in the vineyard are, and to figure out when they can begin harvesting. 

Winemakers need to understand when they should add sugar to the alcohol to ensure it meets the minimum alcohol level, as needed by laws.

How to Calculate the Brix?

Once you are done determining the specific gravity of the solution, you can refer to the numerous conversion tables available. 

While using the Hydrometer, to measure the sugar contents and progress of fermentation, here is what you need to know.

Brix and Specific Gravity Equation 

Brix -> SG Equation:

SG = (Brix / (258.6-((Brix / 258.2)*227.1))) + 1

Specific Gravity to Brix

Brix = (((182.4601 * SG -775.6821) * SG +1262.7794) * SG -669.5622)

Now, there is not a lot of difference between Specific gravity and Brix; they are just two different parameters to measure, just like pounds and kilograms.

Specific Gravity, Brix, & Plato Conversion Tables:

Conclusion 

Remember, Brix and Specific Gravity are different units for calculating the potential alcohol strength in a solution. 

Brix can easily be converted to SG using the following equation – 

SG = 1 +(0.004 x Brix)

Put in simple words, take the Brix Value, multiply it by four and then you have the specific gravity. 

Another formula, which has proven to be more accurate is – 

SG = 1.000019 + [0.003865613(Brix) + 0.00001296425(Brix) + 0.00000005701128(Brix)]

Beer making can be complex – and if you are a beer aficionado, you know that choosing the right beer for you can take a while and there are lots to try, test, measure, and repeat.

Lead marketer, brewer, dad, and husband. Pretty much an all-round awesome guy.