How much does wort shrink or expand from 70 - 200+

[djonesax]

I brewed yesterday and hit my pre-boil volume (13 gallon) and preboil gravity (1.041) using a refractometer. The weird thing was that I also hit my post chilling OG of 1.050 but I was supposed to have 11.2 gallons post boil but I had only 10.5 gallons. So some how I over boiled 3/4 a gallon and still hit my gravity which is really weird.. I wish I had taken a preboil sample for the hydrometer but for some reason just didn’t. Sometimes I get varying readings on the refractometer during the boil but the preboil mash is usually spot on. It was a 60 min boil and I basically put everything into the fermenter trub and all. It seems crazy that I boiled off 2.5 gallons in 60 min and I boiled lightly and before cooling I swear I was just over 11 gallons. I’m wondering if I’m sitting at 13 gallons preboil at 180 degrees how much does that equal after cooling. Maybe i didn’t have as much in the kettle preboil as I thought? Seems shrinkage is only about 4% though.

 

[rburrelli]

Without actually knowing what your volumes were pre and post boil it is hard to say exactly. You should find some way to accurately measure those things going forward. It will help you to know for consistency.

Ther is some shrinkage during cooling, but I don’t know how that is calculated.

 

[djonesax]

I have a calibrated spoon that I use. Pre-boil I was 13 gallons which is what I was expecting to have. Boil I was a little over 11 gallons and I was supposed to have 11.2. But in the fermenter I had 10.5. I didn’t want to put the spoon into the cooled or cooled wort. The fermenter that I normally use is busy at the moment so I used a couple of those homebrew buckets. I guess I should check those gallon markings just in case they’re off

 

[CascadesBrewer]

The BeerSmith default is 4%. For my batches (6 gals at end of boil) that is about 30 oz or close to 0.25 gal. I would guess about 0.5 gal for your batch size. I have not actually measured the difference, but 4% works for me...I figure 0.25 gal for shrinkage and 0.25 gal for lost trub.