Empirical equations have been determined so that Original Gravity, Percentage Alcohol by volume and Residual Gravity can be calculated from the Refractometer Scale Reading and Present Gravity of beer.The equations have been derived from 258 ales and lagers covering a range of Original Gravities from 32 excess degrees (circa 9*P) to 82 excess degrees (circa 20°P). Subsequent testing of the equations suggest that they are applicable to a wide range of beers.The accuracy and precision of these equations are sufficient to permit their use in normal quality control operations. The 95% confidence limits for Original Gravity, Percentage Alcohol by volume and Residual Gravity are, ±1 -8 excess degrees, ±0-30 percent and ±0-45 excess degrees, respec tively.A nomograph has been constructed from the equations to reduce the need for calculation.