Plato Gravity Scale is a measurement of the concentration of dissolved solids in a brewery wort. Degrees Plato (°P) is used to quantify the concentration of extract (mainly sugars derived from malt but also including other soluble material in wort) as a percentage by weight. A 10°P wort will contain 10 g of extract per 100 g of wort. The measurement of wort gravity is important to brewers in that it is an indicator of the potential alcoholic strength of the beer. As a very rough guide, every 1°P generates approximately 0.4% alcohol by volume—a 12°P wort will produce an average of approximately 5% alcohol by volume, depending on the extent to which sugars are fermented out.
The Plato scale differs slightly from the Balling scale in that the measurement of the specific gravity used to determine the dissolved solids content is carried out at 20°C for the Plato scale and 17.5°C for the Balling scale. Brewers measure the degrees Plato using either a calibrated refractometer or a hydrometer.