Formula Confusion !

[crowds]

I have spent the last hour and a half googling for ABV formulas and I'm amazed to see there are quite a few out there each one providing slightly different (sometimes not so slight ) results.
They all seem to start with a basis of (og - fg) but then they change... some even calculate the ABW first and derive the ABV from there.

With such different results (sometimes as much as 0.7%) how can we truly know what the exact content is ?

Is there such a thing as the golden formula that is standard... and if so why do people use others ?

A little confused here

[Dr. Dextrin]

There was a discussion about this on this forum a while ago. I can't remember where, but I made a note at the time that HMRC uses the formula (og-fg)x0.129.

Now while this may or may not be the best formula to use for accuracy, it does have the advantage that it should match the ABV value displayed on all beers that are taxed by HMRC - which means it's probably the best formula to use in practice.

[mick]

Have a look here for HMRC chart

http://www.hmrc.gov.uk/manuals/beerpolm ... L12030.htm

If it's good enough for them

[crowds]

Thanks to both of you

@ Mick
That explains everything !
The factor by which you times it by is not fixed variable explains why it differs.

@ Dr. Dextrin
I see why 0.129 was chosen as the best bet. Because it covers the rang in which most session beers will fall in 3.3 – 4.6.

Thanks again.

A lot less confused now
(well about that anyway, still not sure about the Euro and Lady Ga ga's undercarriage... is she, isn't she ?)

[mick]

She must have a pair

[haz66]

The formula i use is OG - FG / 7.36
ie OG 1041 - FG 1007 = 34 / 7.36 = 4.6% ABV

[6470zzy]

There was a discussion about this on this forum a while ago. I can't remember where, but I made a note at the time that HMRC uses the formula (og-fg)x0.129.

Now while this may or may not be the best formula to use for accuracy, it does have the advantage that it should match the ABV value displayed on all beers that are taxed by HMRC - which means it's probably the best formula to use in practice.

Here is the link to the discussion:

viewtopic.php?f=4&t=28353&p=306968&hilit=abv#p306968