Hi all!

We have been test brewing for a while with the help of Beersmith and will very soon be investing in a 12BBL setup in London and hope to continue using Beersmith.

One thing we have found however, is that the formula used in the program for ABV calculation is not the same as the one used by HM Revenue and Customs to calculate the amount of duty we have to pay on each brew.

Is there any chance we could introduce an option to have it calculated in this way please? I have detailed the method they have for calculating the ABV below (As with anything with HMRC, it isn't easy!!)

When you have taken your readings, calculate the alcoholic strength using the formula:

(OG â€“ PG) x f = a% ABV

Where:

OG is the original gravity of the beer

PG is the present gravity of the beer

a is the beer's alcoholic strength, and

f is the factor connecting the change in gravity to alcoholic strength. The value of 'f' is not constant because the yield of alcohol is not constant for all fermentations. In lower strength beers, more of the 'sugars' available for fermentation are consumed in yeast reproduction than in producing alcohol. The table at 30.3, produced by the Laboratory of the Government Chemist, shows the changing value of â€˜fâ€™ depending on the alcoholic strength of the beer.

30.3 Value of factor 'f' for various alcoholic strengths

(OG - PG) % ABV Factor

Up to 6.9 Up to 0.8 0.125

7.0 â€“ 10.4 0.8 â€“ 1.3 0.126

10.5 â€“ 17.2 1.3 â€“ 2.1 0.127

17.3 â€“ 26.1 2.2 â€“ 3.3 0.128

26.2 â€“ 36.0 3.3 â€“ 4.6 0.129

36.1 â€“ 46.5 4.6 â€“ 6.0 0.130

46.6 â€“ 57.1 6.0 â€“ 7.5 0.131

57.2 â€“ 67.9 7.5 â€“ 9.0 0.132

68.0 â€“ 78.8 9.0 â€“ 10.5 0.133

78.9 â€“ 89.7 10.5 â€“ 12.0 0.134

89.8 â€“ 100.7 12.0 â€“ 13.6 0.135

Also for calculating ABV changes when adding priming sugar for bottling

31. Calculation of ABV when priming sugar is added to beer

(Referred to in section 12)

If you add priming sugar at the maturation stage to promote a secondary fermentation and use the calculation method to ascertain the ABV of the finished beer, you will need to make calculations based on the steps outlined below.

A barrel contains 163.6 litres which comprises 161.6 litres of beer which had an OG of 1040 and 2 litres of added priming sugar with an OG of 1110. The final gravity of the mixture after secondary fermentation is 1010.

1.

Calculate the ABV of the fermented beer using the formula:

(OG â€“ PG) x f = a% ABV

where:

OG is the original gravity of the beer

PG is the present gravity of the beer (that is, final gravity after all fermentation has ceased)

a is the alcoholic strength, and

f is the factor connecting the change of gravity to alcoholic strength(1040 â€“1010) x 0.129 = 3.8

2.

Calculate the ABV of the priming sugar using the same formula:

(1110 â€“ 1010) x 0.135 = 13.5

3.

Calculate the ABV of the contents of the container using the formula:

((Vb x Sb) + (Vp x Sp))/VM = Sm

Where:

Vb = volume of beer in the container

Sb = ABV of the beer in the container

Vp = volume of primingâ€™s in the container

Sp = ABV of primingâ€™s in the container

Sm = ABV of the container contents, and

Vm = volume of container contents.

((161.6 x 3. + (2.0 x 13.5)) / 63.6 = 3.9

Sorry for the long first post!

All info from

http://customs.hmrc.gov.uk/channelsPortalWebApp/downloadFile?contentID=HMCE_CL_000232Cheers