Using the ABV calculator correctly

Discuss all things about brewing beer

Using the ABV calculator correctly

Postby xCamel xSlayer » Thu Apr 06, 2017 12:47

I noticed the other day that there are 4 different settings for our ABV calc at the foot of the page.

I've always left it as the default which is set as "complex".

I just bottled a 1.061 (OG) 1.015 (FG) IPA and the complex theory provides a 6.3% finish, whereas the others give a 6.0% finish.

It doesn't really matter to me so much, but what actually IS the difference here and what should I be referring to?

My target FG was 1.013 and I was expecting that to yield the 6.3% predicted finish, but it seems I still have that 6.3% finishing ABV when I use the complex tab... :scratch: :scratch:
User avatar
xCamel xSlayer
Brewer
 
Posts: 1045
Joined: Tue Feb 09, 2016 17:39
Location: Bradford, West Yorkshire

Re: Using the ABV calculator correctly

Postby Aleman » Thu Apr 06, 2017 14:38

The 'problem' is that different authors have given different formulae for calculating abv, some based on beer and some based on wine (Berry!), and then you have the HMCE throwing a spanner into the works. All of these work on a divisor figure, just what that is depends on the author, but does not necessarily account for the fact that worts (or musts :evil: ) of differing gravities and make up will attenuate differently and therefore have a different abv. At least the HMCE calculator makes some attempt to use different factors for different gravity bands :D.

There is no right formula, or right way to use the calculator, choose one of the 4 methods and stick with it, personally I use the HMCE.

If you want certainty, accuracy, and repeatability then an ebulliometer is the device to buy . . . but they start at around two and a half grand!

please note:The use of punctuation, bold, underlining, italics, and different sized type, follows the convention used in writing, for many years, to place emphasis on the point being made, and to highlight the importance of that point in the opinion of the author. It is not the intention of the author to shout, if that was the case the author would adopt the, much more recent, convention of using all capital letters.
Albert Einstein wrote:Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.
User avatar
Aleman
Curmudgeonly Brewer
 
Posts: 2817
Joined: Thu Apr 03, 2014 00:28
Location: Mashing In Blackpool, Lancs, UK

Re: Using the ABV calculator correctly

Postby xCamel xSlayer » Thu Apr 06, 2017 14:54

Aleman wrote:The 'problem' is that different authors have given different formulae for calculating abv, some based on beer and some based on wine (Berry!), and then you have the HMCE throwing a spanner into the works. All of these work on a divisor figure, just what that is depends on the author, but does not necessarily account for the fact that worts (or musts :evil: ) of differing gravities and make up will attenuate differently and therefore have a different abv. At least the HMCE calculator makes some attempt to use different factors for different gravity bands :D.

There is no right formula, or right way to use the calculator, choose one of the 4 methods and stick with it, personally I use the HMCE.

If you want certainty, accuracy, and repeatability then an ebulliometer is the device to buy . . . but they start at around two and a half grand!


Ha, that's fine mate, I think I'll stick with the formulae here!!
I just hadn't noticed it until now that was all but for the purposes the majority of us brew for, I guess it doesn't really make all that much difference. I'm just happy I've hit almost each and every target of this latest brew, so that's good enough for me!
User avatar
xCamel xSlayer
Brewer
 
Posts: 1045
Joined: Tue Feb 09, 2016 17:39
Location: Bradford, West Yorkshire

Re: Using the ABV calculator correctly

Postby Joe1002 » Thu Apr 06, 2017 15:18

I use the HMRC calcculation which is pretty easy. It's the difference in OG and FG x 0.129 for beers from 3.3% to 4.6% and x 0.130 for beers from 4.6% to 6%. In all honesty, for my own guideline I just use 0.130 for all beers that I brew, it doesn't make that much difference, most of mine are between 4 and 6% anyhow.

A fine beer may be judged with only one sip, but it's better to be thoroughly sure.
User avatar
Joe1002
Moderator
 
Posts: 2742
Joined: Sat Apr 05, 2014 10:01
Location: Essex

Re: Using the ABV calculator correctly

Postby Kev888 » Mon Apr 10, 2017 18:00

I also use the HMRC calculation, just on the basis that its probably closer to commercial beers. Theres a description of their calculation factor, and how this varies with different drops in gravity (between OG and FG), on their site here (scroll down a bit to No. 30).

Kev
User avatar
Kev888
Brewer
 
Posts: 277
Joined: Wed Jul 30, 2014 15:32
Location: UK


Who is online

Users browsing this forum: No registered users and 2 guests