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How much grain in a 5 GAL Mash Tun?

I’m doing my first all-grain brew, Peace Coffee 2d Crack Stout. My mash tun is only 5 gallons (which is fine for the partial mash brews I’ve been doing). HLT is 10 gallons. Obviously, space is limited. The grain bill calls for 12.25 pounds of grains for 5 gallons. Based on what I have learned on this site, I will need 12.25 * 1.25 = 15.3 gallons of water total (which seems like a lot for 5 gallons of beer).

My question is:
Will I have enough room for the 150 mash in? How much water would I want/need? Is it time to just buy the 10 gallon setup?

Thanks for your tips!

Thanks for the link. That has some great info.

The first calculation was for the initial mash. It gave me 4.81 gallons at 164 to get me to a 150 mash temp. That sounds good.

Then I put in the calculation for a 170 mash out and it told me to put in 8.4 quarts of boiling (212) water. I assume this is after I recirculate and drain the first wort into my boil kettle.

Now, that’s over 7 gallons of water in my boil kettle. Do I just need to boil until I get down to 5.25, or the correct gravity? Seems like the total water is a lot of guestimation?


I believe the 1.25 figure refers to quarts per pound of grain, not gallons. That would result in a little less than 4 gallons for the mash which may just fit in your 5 gallon MT. You could then sparge with enough water to reach your pre-boil amount based on your system. From what I’ve read, many mash with 50% of the pre-boil amount and sparge with the other 50%. Keep in mind some of the liquid used for mashing will also be absorbed by the grains and factor that in. Hopefully someone who can explain it better chimes in. The calculator in Pietro’s link is a great resource to help figure this stuff out. You also need to know the particulars of your set up.

12.25 lbs is really pushing it for a 5 gallon mash tun. You can do up to 13, but, A) you are going to be right to the tippy top, and B) if you’re batch sparging you may have to sparge twice.

I try to keep my grain bills at 11lbs or lower, and really like the way it performs with a 9-10 gallon grain bill.

If I need to get to a higher gravity, I just augment with DME or simple sugars in the boil…

Here is a link to the onlline book by Palmer for calculating mash tun size.
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