@BenBe It's how efficient your brew system is taking into account extraction losses boil off ect. Have you read brewers friends low down on it? Here take a look

say you decide to brew with just 2 row malt a 5 gallon batch with 10# of 2 row malt what will you Starting gravity be. efficiency induces dead space or equipment that causes you to brew more than 5 gallons to get 5 gallons sugar conversion in malt starting boil volume evaporation rate from boil efficiency in extract brewing is not that critical except for loss when i brew a 5 gallon batch i am, for 5.25 to account for equipment loss my pre boil volume is 5.75g 5% efficiency change account for 3 or 4 points in sg 70 % 1.052 75 1.055 80$ 1.059 so in this 5 Gallon batch it accounts for 1/2# of grain so this really matters if your trying to hit a target abv

It's the ratio of the extract - sugar - you actually got into the fermentor to the potential extract - sugar - in the grains and adjuncts you used to make the wort. With extract it's easy: Efficiency of the extract you use is 100% - all of the sugar makes it into the fermentor, the only losses are the wort absorbed by the hops. Steeping generally doesn't get all the sugar in the grain, nor does mashing. When your brewhouse efficiency is 70%, that means you got 70% of the theoretical maximum extract of the grain, extract or adjuncts into your fermentor. I say "theoretical" because you can never achieve the actual maximum extract, so a standard test called a Congress mash (in the US) is used to determine that maximum.

Thanks guys for your answers, I am french canadian. So I am starting, per example, with 7 gallons of water, 10 pounds of all grain, 6,25 gallons to boil, 5,25 to fermentors, 5 gallons into bottling, Will my brew house effiency be like 5 / 7= 72%?

Brewhouse efficiency is a measure of how well you converted the starches into sugars, not the relationship between beginning and finishing volumes. The grainbill can be entered into the handy Calculator on this site and your values achieved throughout your brewday to determine Brewhouse efficiency.

Nope...Click on the question mark beside the Target: Kettle/Fermenter box in the calculator and it'll take you to the page that explains all the terminology. 4) Brew House Efficiency: An all inclusive measure of efficiency, which counts all losses to the fermentor. This can be thought of as 'to the fermentor' efficiency. Brew Log Type - 'Brew Day Complete'. Gravity - OG, measured after cooling, and before pitching yeast. Volume - how much wort made it into the fermentor. All losses that do not make it into the fermentor are counted against this measure, including hops absorption (which varies by recipe), and trub losses.

My apologies. I should have stated that "in part", Brewhouse efficency... As I said earlier, other more experienced brewers will chime in, and you have. I will leave it to you all from here.

It gets confusing...I still ignore "Conversion Efficiency" in the Brew Session Log because I have no idea why it should be different from "Pre-boil Efficiency" if the volume and gravity numbers are the same.

No. The 10 gallons of grain has a theoretical yield of 37 gravity points per pound of grain per gallon - 370 gravity points. In a typical mashing situation, you get 31 ppg, 310 gravity points. The efficiency is 310/370, or 83% conversion efficiency in that scenario. That's the first efficiency in the listing, conversion efficiency. Sugar is 46 points per pound per gallon so your 310 points equals 6.74 pounds of sugar in your wort from a theoretical maximum of 8.04 pounds. Every efficiency after that is based on the amount of sugar you leave behind in the mash tun (what the grains have absorbed) and the kettle (trub and hop absorption losses) as well as any "dead space" losses (the amount of liquid wort remaining under your mash tun's false bottom, etc. I'm interested in conversion efficiency just because, and brewhouse efficiency because that influences how I formulate recipes. Pros worry about other efficiencies because of the cost of grain, not much of a factor in our 5 gallon batches.

No, the only way to know what your efficiency is would be to brew a batch of beer and keep good track of your grain weight, wort volumes and gravities. You can then take these numbers and input them into the Brewhouse Efficiency calculator under the tools menu on this site. For example, you start with 10 pounds of grain (such as Canadian pale 2 row) mash it, boil the wort, chill it and put it in the fermenter. You measure the volume and have 5.5 US gallons and you measure the gravity as 1.047. Put these numbers into the calculator and it will tell you that your efficiency is 72% (71.81 to be exact). What this means is that of all the potential sugar in that 10 pounds of grain, 72% of it made it into your fermenter. Now that you know this, when you formulate a recipe, you can input this number in the recipe calculator and the software will be able to give you an accurate prediction of your original gravity. But to know your efficiency you will have to brew at least one batch and keep track of your numbers.