Plato scale

Lore & Background

The Plato scale was developed in the early 1900s by German chemist Fritz Plato and his collaborators, who made further improvements to earlier scales. It is essentially the same as the Balling and Brix scales, with improvements in accuracy and reliability in the newer versions, since they are all based on mass fraction of sucrose. The tables for the three scales differ mainly in their precision and in the temperature at which the measurements are to be made. A rough conversion between specific gravity and degrees Plato can be made by dividing the thousandths of SG above 1 (gravity points) by 4. For example, a specific gravity of 1.048 has 48 gravity points, and 48 divided by 4 gives approximately 12 °P. More accurate formulas exist, such as °P = 260.4 - (260.4 / SG) when measured at 20 °C. American brewers use a mixture of degrees Balling, degrees Plato and specific gravity, while home wine, mead, cider, and beer makers typically use specific gravity. The scale is used to determine the 'size' of the beer, its alcoholic strength, and how much of the available sugar the yeast was able to consume.

Reader's Guide

The Plato scale is significant in brewing as a standardized method for measuring the extract content of wort and beer, which directly relates to the potential alcohol content and body of the finished product. According to the source article, it is one of three closely related scales (Balling, Brix, Plato) that all measure the mass fraction of sucrose, with Plato being the most refined version. Its use is particularly prevalent among British and continental European beer brewers, while American brewers may use a mixture of scales. The scale allows brewers to calculate original extract (OE), often referred to as the 'size' of the beer, and to estimate alcoholic strength through gravity measurements before and after fermentation. In Germany, the original extract is often printed on the label as Stammwürze, and in the Czech Republic, beers are commonly referred to by their degree, such as '10 degree beers' or '12 degree beers'. The Plato scale thus provides a consistent framework for brewers to communicate and control the sugar content and resulting characteristics of their beers.

Did You Know?

• A rough conversion from specific gravity to degrees Plato is to divide gravity points by 4.
• British and continental European beer brewers generally use degrees Plato.