Anyone know what volume a pound of grain takes up in a mash tun? I’d like to be able to calculate what the max amount of water I can add to my mash tun if it has X lbs of grain in it. This way I could figure out what my maximum mash-in volume would be (and therefore, maximum weight of grains the mash tun can handle and still be properly mashed) as well as maximum batch sparge volumes.
i can usually fit a pound of milled grain (takes up more volume than unmilled) in probably about a half gallon space. simple enough to figure. get a pound of milled grain and put it in a large measuring pitcher
Not so simple - there is a lot of empty space in between the grains in that 1/2 gallon. That space can be filled with mash water. I could figure this out myself, but I don’t have a pound of grains to try it with.
many of the brewing programs will help you with this.
oh wet grains, that is different, but if you still have total volume of grain (dry) and total volume of liquid, you won’t exceed their sum if you are just trying to make sure you don’t exceed capacity. even considering the hidden space, this changes also with absorption.
The typical figure is 0.36 qt per lb of grist. That’s for the material that remains once the starches has been dissolved.
It’s what’s built into most calculators, including this one: Green Bay Rackers--Mash Calculators
I can typically fill a standard 6.5 gal plastic fermentation bucket almost to the top with 20 lb of milled grain. That equates to about 3.3lb/gal.
So a pound of grain has a volume of 0.3 gallons.
Malted barley has a density of 31lb/c.f… Water has a density of 62.4lb/c.f.
The volume of 1 gal of water is 0.133681 cubic feet. So 1.5 qts of water has a volume of .05c.f.
1lb of malted barley has a volume of .032c.f. Therefore .05 +.032 = .082c.f.
1 cubic foot = 29.9220779 US quarts * .082 = 2.45 quarts total volume. 
Thanks. I’m guessing now that beersmith does this when calculating batch sparge volumes. Although in the past it has occasionally told me to use a pre-boil volume that was greater than my kettle!
The answer is likely to differ with uncrushed grain vs crushed.
Different crush settings are also likely to change your result by slight amounts.
I know it seems crazy, but if you take a 5 gallon bucket & fill it with uncrushed grain, I’d be willing to bet you will have trouble fitting it all into the same bucket, after crushing.
So true. I tried to put a bag of crushed malt back into its original bag and it barely fit.
I had to come back and read that again. The first pass I read that it barley fit. :