OK, You asked for it. The exact formula (minus raised exponents) for converting specific gravity to Brix is as follows: °P = 135.977 x sp gr(3power) -630.272 x sp gr (2nd power) +1114.14 x sp gr - 616.868. I use brix to watch the thinning runoff and a hydrometer to sample O.G. and F.G. The third scale on the hydrometer is a fairly accurate estimate alcohol by (I believe) weight. My old mercury lab thermometer broke but the mercury was recycled. Rick