I'm trying to understand the difference between Mash Efficiency and Brewhouse Efficiency.

Is Brewhouse Efficiency essentially the efficiency of Mashing AND Lautering, whereas Mash efficiency would be the efficiency of just the MASH itself and NOT the Lauter?

I see in John Palmers book, that Mash Efficiency is calculated the same way that a BeerSmith blog post tells me to calculate Brewhouse Efficiency.

Are these terms synonymous among home brewers due to the volume of the brew kettle?

4 Answers 4


In principle, brewhouse efficiency measures the yield of the entire process (how much beer you bottle) against the theoretical yield, while mash/lauter efficiency measures specifically the extract from mashing and lautering. However, typically brewhouse efficiency means efficiency into the fermentor. This is the most useful definition, since it takes into acocunt typicall losses that occur constantly from batch to batch.

Brewhouse efficiency includes lauter efficiency and also other losses in the brewing process after lautering, such as losses in the kettle (trub/hop absorption), losses the chiller, in racking and to trub.

The numbers and figures can get involved, although a brewkaiser gives a comprehensive (and comprehensible!) rundown of the different types of efficiency measurements in brewing.


It is only since the advent of homebrewing software that brewhouse efficiency has also meant 'to the fermenter'. Before homebrewing got involved, brewhouse efficiency was only known as efficiency 'to the kettle'. There were two flavors, outlined in the bruakaiser article link in mdma's answer, but both involve 'to the kettle'.

Also in the BrauKaiser article, it explains how the BeerSmith people, to name one software package, decided to take it upon themselves to redefine brewhouse efficiency as 'to the fermenter'. Contrary to the claim in mdma's answer that 'to the fermenter' is the most useful definition, Braukaiser also wrote about how useLESS the 'to the fermenter' defintion is, especially for sharing recipes. Why mdma's answer linked the braukaiser article, then contradicts that same article, simply adds more confusion to an already confusing issue.

Why fermenter based 'brewhouse efficiency' is useless is that, contrary mdma's statement that all losses stay the same from batch to batch, they do not. As noted in Bryan's answer, different hop bills result in different kettle losses. This requires adjusting fermenter based 'brewhouse efficiency' for every recipe if those losses are entered into the software. An alternative is to increase the fermenter volume, and manually account for the losses included in it, but then what is the point of using software and 'to the fermenter efficiency'.

Using 'to the kettle' brewhouse efficiency would simply require increasing the target kettle volume (and ingredients to match the increase), to account for hop/trub losses specific to a recipe. Nothing has changed except losing some final volume, so why should anything change except the post boil volume, so that the fermenter target volume is still correct?


AFAIK, brewhouse efficiency takes kettle losses into account and simply looks at the volume in the fermenter to calculate efficiency. Mash efficiency usually takes both the mash and sparge into consideration, but can also refer to only the mash.

  • The way I think of brewhouse efficiency is: how much sugar did I get into my fermenter? How much potential sugar was in the grain bill? The first divided number by the second is the brewhouse efficiency. Mar 26, 2012 at 18:29

My understanding:

Mash efficiency measures the gravity and volume into the boiler at the start of the boil, i.e. how well you got the sugars out of the grain.

Brewhouse efficiency measures the gravity and volume into the fermenter.

I spend quite a while confused as to what these numbers were and what I should be using in recipe planning software such as BrewMate.

Recipe planning software typically has you set your efficiency at (for example) 75%, set your brewlength (23 litres), and has you enter your grains. It then calculates your OG for you.

But this (at least in the software I've used) isn't affected by the hops you specify, or the deadspace in the boiler, or the length of boil and rate of evaporation. The brewlength isn't the volume you want in the fermenter, it's the volume you want in the boiler after cooling, and I hadn't realised this so I kept plugging in the volume I wanted in the fermenter.

I was finding that with a hoppy beer I'd end up with lower volume into the fermenter than I wanted, but maybe at the same gravity, and this certainly wouldn't be the 75% efficiency. If it was a shorter brewlength I'd also be out, as the deadspace would make up a bigger percentage, since it's a constant volume.

These days when I use recipe planning software I set my efficiency at 75% and formulate the recipe for the gravity and volume I want in the boiler at the end (26 litres, say), guesstimating 3 litres of loss to the hops and my boiler's deadspace, a little more if it's a very hoppy recipe, so I end up with the right sort of volume into the fermenter (23 litres).

Everything now seems to work out as I expect; I get both volume and gravity about as planned at the end of the boil, and the only variation is a minor one of the volume into the fermenter.

Or am I still confused? ;-)

  • I think you need better software :) I use Beersmith and it has fine grained controls over train absorption, mash dead space, kettle dead space, etc. It takes a while to get the right numbers dialed in, but then determining water volumes and grain weights is a breeze. Other popular programs are Beer Tools and Pro Mash. I expect they have similar controls. May 22, 2012 at 14:05

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