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51% efficiency?

So I just finished up my Russian Imp. Stout. I usually get about 68% efficiency on my 1.060 OG beers (I use Northern Brewer’s mill) and I planned on losing quite a bit of eff. with this bigger beer. However, I lost a LOT more eff. than I planned. I was hoping to be in the 1.110 range at 63% eff. (what I was shooting for). My OG ended up being 1.088 which is about 51% eff.

Do you think that this eff. loss is typical and I just overestimated my expected eff. or do you think there’s something else at work? I know the setting on Northern Brewer’s grain mill is.040 so I know that’s at least part of the problem.


If you normally get 68%, 51% for a batch with that OG isn’t unreasonable. I think you overestimated.

My mill is set at 0.060" gap and I get 80%, I wonder how gap compares if at all from mill to mill?


Very typical. In fact, I find gravity points plus efficiency points to form nearly a constant that can be applied to any beer for a particular brewer and his/her crush and system. Find out your constant and you’re good to go. Actually, with higher gravity beers, the “constant” increases, such that 51% is about the lowest efficiency you will see for any beer up to about OG=1.100. Here’s how this works.

Say for an average beer of about 1.060 your average efficiency is 68%. Okay, so then your constant is 60+68 = 128. So then say you want to make a beer at 1.080. Okay, so subtract 128-80 = 48% efficiency to expect for that beer. But in reality, you’ll never get below 51%, so figure maybe you’ll get around 56%, something like that.

The same correlation works on the other end. For a 1.040 beer, I would expect your efficiency to be around 128-40 = 88%, or maybe a bit lower… maybe you’d hit 82%, somewhere around there.

The closer you are to 1.060, the more accurate this “constant” correlation is.

I just brewed a batch of Denny’s Old Stoner BW last weekend and “only” got 51 % efficiency. OG = 1.097

Usually I get low to mid 70’s on my system. Batch sparge.

I have brewed this recipe for the last 4 years and always get right around 50 % (1~2%) for that big of a beer.

The partigyle came in at a “whopping” OG = 1.051. 26 %! (Forgot to stir before I ran off. May have lowered efficiency a little bit).

I’d say you got very realistic results from your brew day on that size a beer.

Hope the beer kicks arse!

I use NB’s mill as well — for bigger beers like this, I’ll do a couple sparges and a 90 minute boil to get about 60% efficiency.

I agree, that seems reasonable. For really big beers, you may want to reduce the size of your runnings and go for three instead of two, that will give you a bump. Or you could just go for three normal sized runnings and boil longer. That will give you a big bump.

I did an imperial stout with 23 lbs of grain and ended up with 5.5 gallons of 1.103 (post-boil). Efficiency was 69-70% and I did three runnings (two sparges).

EDIT: I also had a friend helping me and we both stirred until our arms were numb.

FWIW, I just made a beer Saturday of average SG 1.055 and I saw over 80% with a single crush at NB’s St Paul store. I was talking to them about a prior beer and he made mention that it was just recently set at 0.035 I believe they can go that low as the rollers are well used. I have always hit minimum 75% typically 80% for average strength beers over the last 12 months before it was recently gauged also.

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