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UK Brewer Question: ABV% calculation

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  • UK Brewer Question: ABV% calculation


    This is a question about what ABV% I should give my racked beer.

    In my last brew session I used a yeast starter pitched directly on top of the transferred cooled wort from the copper.

    The yeast starter was WLP013 pitched some 36 hours earlier into 84 litres of pale malt-only wort. Its OG was 1.0488. The starter was very, very active at the time of pitching.

    The main brew, measured before pitching the yeast starter, was 500 litres of wort at 1.0417.

    The combined OG of the 584 litres was 1.0405.

    The amount collected at the end of the process has been 584 litres - 14 nines plus a little extra.

    Foolishly, and possibly recklessly, I forgot to measure the SG of the yeast starter at pitching but I have worked backwards and derived an SG of 1.028 at the time of pitching, given the SG of the combined worts.

    Now, the wort has fermented out to 1.0092 and so my question is, what is the ABV% calculation for duty purposes in this case?

    Is it:

    OG of combined wort 1.0405
    RG of of combined wort 1.0092

    40.5-9.2 = 31.3 x 0.129 = 4%


    OG of starter 1.0488
    RG of starter 1.0092

    OG of wort 1.0417
    RG of wort 1.0092

    ABV% of starter 48.8-9.2=39.6 x 0.130 = 5.1%
    ABV% of wort 41.7-9.2=32.5 x 0.129 = 4.0%

    ABV% of whole is:

    ((5.1 x 84) + (4.0 x 500))/584 = 4.15%

    I have had another good read of Notice 226 but cannot immediately see that this situation is dealt with.

    I suspect putting 4.1% would keep both HMRC and the Trading Standards happy? Isn't there an acceptance from Trading Standards that ABV% can be +/- 0.5% up to 6% beers?

    I suppose I just want to know the right thing to do here.

    Any thoughts would be very gratefully received.

    Many thanks in advance.
    Kind regards