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BIAB Est ABV and OG Different to Measured ABV and FG


Oct 12, 2014
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Hi, I am loving Beersmith and have been having a great time designing beers and brewing them.

I have noticed in my last brew that the target OG was WAY off. On further investigation I noticed that the measured OG was a lot different to the estimated OG. ie. 1.046 vs 1.070

Can anyone help me resolve why this is the case?

I use a 40L BIAB urn setup. I am happy to post recipe stuff here if that helps.

I have tried altering mash types and everything but it remains the same. Could it be a issue with an ingredient that I am using to mash?

I would love to know how I can make a 7% ABV IPA BIAB instead of a 4.6% one.

Any help would be greatly appreciated.  ;)


Grandmaster Brewer
Sep 6, 2011
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Ventura, CA
Based on your description, it appears that your brewhouse efficiency is set too high.

Based on your gravity, it seems that your grain crush may be too coarse.

Brewhouse efficiency is the percentage of TOTAL sugars that make it to your fermenter. Mash efficiency plus trub loss (as a % of total kettle volume) are what reduce your efficiency from 100%.

"Normal" recipe specs are:
70% Mash Efficiency
5.5 Gallons in the Fermenter
0.5 gallons trub

Then your brewhouse efficiency should be about 65%.

To meet the specs above, this brewhouse efficiency would require 16# to 17# of grain for 1.070.

Is that close to the grain weight you've used?