Have been using OG-FG/7.5, but seen figures ranging from 7.4 to over 8 for the same calculation
Are the rather involved calculations I've seen on the web any more accurate? I don't mind doing the tricky maths if the result is better.
ABV
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Harry Lime
ABV
I like to know my brew ABV fairly accurately and wondered which is the best method.
Have been using OG-FG/7.5, but seen figures ranging from 7.4 to over 8 for the same calculation
Are the rather involved calculations I've seen on the web any more accurate? I don't mind doing the tricky maths if the result is better.
Have been using OG-FG/7.5, but seen figures ranging from 7.4 to over 8 for the same calculation
Are the rather involved calculations I've seen on the web any more accurate? I don't mind doing the tricky maths if the result is better.
Re: ABV
I can't give a definitive answer here, but all the estimates for ABV are just that - estimates. Several things affect the amount of alchohol produced from a certain level of OG-FG change, including:
type of sugar (not all sugars are equal in their increase in SG
how much growth the yeast has to do (during which time it will use sugar, but not produce alchohol).
presence of other microorganisms (not necessarily giving off flavours)
etc
So what we do is make a guess at some or all of these effects and determine how much alchohol is in the final product. When I started I used a complex online calculator. Then I lost the link, so I started to use (OG-FG)/7.5. I checked some of my earlier calculations against this and was rarely more than 0.1%ABV different, so I kept with the easier version. Of course if you brew very strong or weak beers this approximation may be less accurate, but I find it OK for what I brew.
Hope this helps
GTI
type of sugar (not all sugars are equal in their increase in SG
how much growth the yeast has to do (during which time it will use sugar, but not produce alchohol).
presence of other microorganisms (not necessarily giving off flavours)
etc
So what we do is make a guess at some or all of these effects and determine how much alchohol is in the final product. When I started I used a complex online calculator. Then I lost the link, so I started to use (OG-FG)/7.5. I checked some of my earlier calculations against this and was rarely more than 0.1%ABV different, so I kept with the easier version. Of course if you brew very strong or weak beers this approximation may be less accurate, but I find it OK for what I brew.
Hope this helps
GTI
Drinking: Kriek (cherry beer); prohibition coconut rum; Davey's Best Bitter 2 (AG); TC; Mead; Gorse Wine; Darwin's summer ale; Apple wine
Conditioning: Grape wine 2009 & 2010; Pomegranate and cherry wine
Brewing: Vinojay (orange wine); Vino de tavola - rosso
Planning: Newton's Porter
Gone but not forgotten: Mead; Framboos (Kit); Gorse wine;
Conditioning: Grape wine 2009 & 2010; Pomegranate and cherry wine
Brewing: Vinojay (orange wine); Vino de tavola - rosso
Planning: Newton's Porter
Gone but not forgotten: Mead; Framboos (Kit); Gorse wine;
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boingy
Re: ABV
There is an interesting thread about it here:
www.jimsbeerkit.co.uk/forum/viewtopic.php?f=6&t=31681
Just don't be expecting any firm conclusions!
www.jimsbeerkit.co.uk/forum/viewtopic.php?f=6&t=31681
Just don't be expecting any firm conclusions!
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Kev888
- So far gone I'm on the way back again!
- Posts: 7701
- Joined: Fri Mar 19, 2010 6:22 pm
- Location: Derbyshire, UK
Re: ABV
I too understood that the change in density is a consequence of other influences too - which you may be able to compensate for mathematically but still won't provide a direct measure.
The effect on the body, raising of blood alcohol and rate of metabalism is not a precisely predictable thing either, so for any practical purposes as long as I can gauge 'aproximately' how much I'm drinking then I'm happy. I don't sell beer, but if I did what would matter there is presumably matching what customs/excise require rather than achieving ultimate accuracy.
Is there a reason why you need greater accuracy, or is it just a case of choosing between the options?
Cheers
Kev
The effect on the body, raising of blood alcohol and rate of metabalism is not a precisely predictable thing either, so for any practical purposes as long as I can gauge 'aproximately' how much I'm drinking then I'm happy. I don't sell beer, but if I did what would matter there is presumably matching what customs/excise require rather than achieving ultimate accuracy.
Is there a reason why you need greater accuracy, or is it just a case of choosing between the options?
Cheers
Kev
Kev