Calculating %ABV

Physics, chemistry and biology of brewing. The causes and the effects.

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Calculating %ABV

Postby llama » Wed Feb 05, 2003 10:21 am

It's driving me crazy! everyone i talk with and evey book and web site i visit give different (and disagreeing) equations and methods. Is there a tried and true equation? What do the big brewers use?
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Postby Brewer2001 » Wed Feb 05, 2003 10:40 pm


Most large breweries measure using one scale or the other not both. There are some non-liniar values between the SG and Plato/Balling scales.
Someone had a similar question a while back, I don't know if we found an answer. I use this at home SGo/SGf *105 = ABW; ABW * 1.25 = ABV. Barring errors in readings the calculations come fairly close to the readings (I went back through my brew logs). In the brewery I have used saccrometers that read Deg. Plato and have correction thermometers built into the float.

I hope this helps.

Good brewing,

Tom F.
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i see

Postby llama » Thu Feb 06, 2003 4:12 am

Thanks Tom for your help. I'm assuming that you'r equation should read "(SGo-SGf)*105=ABW". That brings me close to what I was figuring. I also took a good look at my hydrometer and calculated a ABV from it "(SGo-SGf)/7.5=ABV".
ABV is what most breweries quote, isn't it?
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To ABV or ABW.. that is the question...

Postby Mesa Maltworks » Thu Feb 06, 2003 11:31 am

"ABV is what most breweries quote, isn't it?"

In the USA, the individual states mandate what alcohol statistics are required on labels printed by producers. Some are by weight (like where I am now) and some are by volume, like the state I recently left.

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Postby fitz » Mon Feb 10, 2003 8:42 am

Most cans, bottles, labels refer to ABV and not ABW. Even imports from belgium,etc. list this on their packaging.
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