Dumb effeciency question.

I have yet to brew an AG batch. First I want to be a theoretical expert before i physically dive in to this. I'm not exactly sure what you all mean when you say x% effeciency. I guessing that this is a percentage of sugars that you are extracting from the total available starches? Everyone will say that they are having something like 69% or 71%, how do you calculate this so precisely? thanks for helping me clear this up? happy brewing!

Efficiency is basically a calulation of the % of fermentable sugars you have extracted from the grain through your mashing process.

For example, say you mash 10lbs of pale 2-row. The max amount of fermentable sugar that can be extracted from this would yield a gravity of about 1.073 (This would be 100% efficiency - this is given based on the ingredients added)

If prior to pitching the yeast you take a gravity reading and you have 1.055 then you have 75% efficiency. Meaning that you have extracted 75% of the potential fermentable sugars from the grain. >>>>>>> 55/73 = 75%

If you use a brewing software such as beersmith you can calculate more precisely by inputting all your ingredients and then telling it the gravity that you got after you are done mashing. Theres a free trial download I would suggest downloading and toying with. It helps you calculate water temps and volumes in order to hit your targets. There are also adjustment calculations for if you miss your targets and need to adjust.

Im about to calculate my efficiency, but kinda wierded out on it. Dont I have to calculate for the grain soaking up water, and also water lost to steam ? ?

The grain absorption and evaporation rate will effect the total water volume that you need to end up at five gallons (or whatever volume you are shooting for). It won't effect your effieciency. Your efficiency will be calulated based on the grain making up your grain bill and your original gravity (gravity just prior to pitching yeast).

If you take a pre-boil gravity you can get an idea where you will end up after boil. Typically you will lose a gallon per 60 minutes of boiling which will increase your gravity about .01 (assuming a five gallon batch)

Again, using a software such as beer smith can help you get a better idea as it will calculate the grain absorption for you and tell you what starting water volume to use to end up with five gallons in the end.

Yup. You need to tKe those things into account. Yet another thing beersmith will do for you. Anyway, you want to base your efficiency on the volume of wort you have after you boil. However, you can calculate your extraction efficiency based on the gravity of your pre-boil wort. Take a reading before you boil and use the volume you have at tha time to do your calculations.

It's a bit of trial and error at first but you should get close. Take good notes if it is your first batch so if you end up short or with too much volume you can identify what caused it.......

specific things to note.

Mash tun dead space (how much liquid left in the tun after run off)

Water volume pre-boil and after boil (so that you can figure out how much liquid you boil off with your specific pot and burner)

Just take as detailed notes as possible with the first batch is my advice.

Read Kaiser's Understanding Efficiency for great info.

I use a 'total gravity points' system, which is just one way of doing it.

Each grain type has a certain amount of extractable sugars (i.e. potential) that has been determined by a lab. We usually don't know the exact number (which varies from crop-to-crop) but we usually have a pretty good idea just based on the type of grain it is. You can use the numbers from the Wiki Malts Chart.

So the chart says that 1 pound of Maris Otter in 1 gallon of water yields a gravity of 1.038. Sometimes this number is given as 'gravity points' in ppg (points per pound per gallon). So 1.038 is the same as 38 gravity points. And this 'potential' is at a theoretical 100% efficiency. So if you used 10 pounds of Maris Otter in 5 gallons water and got 100% efficiency you'd have: 38 points/pound/gallon times 10 pounds divided by 5 gallons = 38 * 10 / 5 = 76 points (so your OG at 100% efficiency would be 1.076). But you won't get 100% efficiency, you'll get less.

Using 'Total Points' you leave the volume out of the calculation (for now). So 10 pounds of Maris Otter at 38 ppg = 10 * 38 = 380 total gravity points. That's the theoretical max number of total points I can get (no matter what my volume is). At any point during the brewing process I can take a hydro reading, convert that gravity to points, and then multiply the result by whatever volume I have to get the total points I actually have. So if I have 6.25 gallons of 1.051 wort, I multiply 51 by 6.25 to get 318.75. If I then divide by the theoretical max points I get my efficiency up to that point in the brewing process. So 318.75/380=.84 or 84% efficiency.

It should be apparent that it's the combination of your gravity and volume that determine exactly just how much potential you extracted. So you need to be able to measure both your gravity and your volume as accurately as possible. Remember water expands as it heats so 5 gallons of water @ 170 degrees F will measure more than 5 gallons...you need to account for this. It's in Kaiser's article.

This is some great information. thank you