abv

[barry field]

dear all does any body here know how to use a refractometer or convert the reading to alcohol levels , we tested some chardonnay with a known abv of 14 % and it came in around 7 ,when we tested our cider it was around 9 , are we assuming its stronger , can any one help please

[Andrew Lea]

Sorry but you can't use a refractometer on its own to measure alcohol
levels. That's because the refractive index is set by a combination of
the alcohol plus residual sugar levels and non-sugar solubles such as
glycerol, sorbitol etc.

But if you have readings of the SG before and after fermentation you
can divide the difference in the readings by 8 which gives a pretty good
estimate of ABV%.

Andrew

--
Wittenham Hill Cider Portal
www.cider.org.uk