Algorithm To Calculate Alcohol Content

(O.G. * F.G.) * 100 * CF = Approximate ABV where O.G. = Original Gravity F.G. = Final Gravity CF = Conversion Factor

I use CF = 1.3. You can find the exact number somewhere Given the precision and the readability of hydrometers, this is similar to using a micrometer with a broomstick on the end of it.

Dick

Don't you mean (O.G. - F.G.) * 100 * CF = Approximate ABV

(Subtract FG from OG, not multiply them)

OG-FG*(factor)

The factor can be between 0.125 and 0.135 depending on the strength of the beer. Using 0.130 is good enough for homebrewing purposes but the following table has them all. OG and FG are used as whole numbers (eg 1040 rather than 1.040). The factor varies because in weaker beers a greater percentage of the available sugars are used for yeast growth and less is left for alcohol production.

(OG - FG) % ABV Factor Up to 6.9 Up to 0.8 0.125

7.0 - 10.4 0.8 - 1.3 0.126 10.5 - 17.2 1.3 - 2.1 0.127 17.3 - 26.1 2.2 - 3.3 0.128 26.2 - 36.0 3.3 - 4.6 0.129 36.1 - 46.5 4.6 - 6.0 0.130 46.6 - 57.1 6.0 - 7.5 0.131 57.2 - 67.9 7.5 - 9.0 0.132 68.0 - 78.8 9.0 - 10.5 0.133 78.9 - 89.7 10.5- 12.0 0.134 89.8 - 100.7 12.0- 13.6 0.135