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Maximum grain to mash

In a fit of boredom at work, I decided to try to figure out the maximum amount of grain I could use for a 5 gallon batch. It’s not the most useful information, but I was bored, so here’s my answer and the assumptions I made to get it.

No sparge mash with a minimum of 6.5 gallons or 26 qt of liquid wort collected.

1.5 qt water/lb grain

.8 qt water absorbed/lb grain

This results in a maximum of 0.7 qt of wort collected per lb of grain.

So 26 qt x 1 lb/0.7 qt = 37.14(and lots more numbers after the decimal) lb of grain max per batch.

With the amount of sugar left in the mash, I’d sparge two additional batches out of this. Could be a fun group brew day.

You can also use the “Can I Mash It?” calculator at

Absorption may be a bit high.

.8 qts per pound - that’s .2 gallons / lb.

.4-.5 qts per pound is normal - that’s .1 - .125 gallons / lb.

Also, lowering your qt/lb ratio would allow you more grain, but may change the nature of the mash.

1 qt/lb with .5 qt/lb absorption would allow 52 lbs of grain to be mashed!

I’ve seen mashes as low as .9 qt/lb

So, yes, you can just buy a 55 lb sack of base malt to make a 5 gallon batch of beer!

(Not sure what you’d end up with, but hey, if you try it, let us know!)

I was REALLY bored.

Are you guys talking about the same thing?

Denny is pointing to an “Is your mashtun big enough?” calculator.

Sampothepancake seems to be answering the question of how many pounds of grain can be mashed with a single infusion to get a certain amount of wort.

Of course, if you decide to brew with 37lbs of grain then you’ll need a big mashtun and the mash tun calculator would come in handy.

37lbs of grain @ 1.5qts per pound will require min. 17 gallons of space.
55lbs of grain @ 1.5qts per pound will require min. 25 gallons of space.

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