# BIAB Efficiency

I’m brand new to BIAB and am wondering the best way to figure efficiency. When do I do it? After the boil? After mashing? How do I do it?

I would measure the preboil gravity and volume and do it that way.

Is this right, formula wise: Gallons of Wort Collected times Gravity divided by Malt Pounds?

Gravity points (1.050 = 50 points) times gallons = points collected.

36 points per pound in malt (an average value) times pounds of malt = theoretical points

collected points/theoretical points = efficiency

Example:

10lb of grain gives you 6gal of 1.040 beer.

6x40=240
10x36=360
240/360=67% efficiency

This depends of if you’re doing a full boil or partial. I was doing BIAB with partial boils and am now up to full boils since I bought a turkey frier with 30qt pot. But I don’t bother with a gravity reading until after my wort is cooled and in the primary. After aerated and just before the yeast is pitched.

Either way (full or partial boil) you need to account for your boil volume if you are taking a reading before boil. If you are boiling only 3 gallons and topping off to 5, your gravity readings will be way off from what you’d want your final 5 gallons of wort to be. It will be much higher. And again, if you’re doing a full boil and starting with 6+gallons, your preboil gravity will be lower that what you’d want your final 5 gallons of wort to be.

Efficiency isn’t affected by the boil volume. I suggested doing it preboil simply because that tells you how the mash went. If you calcualte what goes in the fermentor (brewhouse efficiency) you’re going to include any losses from throwing out trub or things like that. Kind of depends on what you want from your number, I guess I assumed the idea was to check whether the BIAB mash went well. You’ll know from a preboil gravity if you’re going to hit your target OG at the volume you’re after, and you can adjust the boil time to hit your OG if thats important to you.

I can get 75% efficiency from a no-sparge mash, and just a few points better from a sparge mash. Thats using my quick and dirty 36points per pound for my total malt bill, not calcualting each ingredient separately. I’m just looking to be in the ballpark on gravity.

[quote=“tom sawyer”]Efficiency isn’t affected by the boil volume. I suggested doing it preboil simply because that tells you how the mash went. If you calcualte what goes in the fermentor (brewhouse efficiency) you’re going to include any losses from throwing out trub or things like that. Kind of depends on what you want from your number, I guess I assumed the idea was to check whether the BIAB mash went well. You’ll know from a preboil gravity if you’re going to hit your target OG at the volume you’re after, and you can adjust the boil time to hit your OG if thats important to you.

I can get 75% efficiency from a no-sparge mash, and just a few points better from a sparge mash. Thats using my quick and dirty 36points per pound for my total malt bill, not calcualting each ingredient separately. I’m just looking to be in the ballpark on gravity.[/quote]

I realize eff isn’t effected by the boil, but figuring out your eff is absolutely dependent on when you test it (preboil, postboil, etc)… like you pointed out.
My point being if he inputs a recipe into a program and he inputs say 75% estimated eff and then does a pre-partial boil gravity check, that number will be wildly different than what the program is coming up with. I was just trying to state the obvious since the OP mentioned he’s knew to all grain brewing.

Thanks again guys. If my efficiency comes back less than what I’m looking for, is there a way to correct it?

There are a lot of factors that go into efficiency. Grain age, grain crush, water temp, water chemistry, water volume, etc… It goes on and on. I would think the best thing to do would be to start with a recipe with a simple grain bill. Brew it and see where you’re at. When done, post the recipe with detailed mashing instructions on this site and get some feedback.

With BIAB, there’s no reason you can’t consistently be somewhere between 70%-80% efficiency.

This has been a big help. I will definitely post a detailed recipe and let you know how it went. All the equipment was on my doorstep this afternoon. Can’t wait to set it up and get started!

Micah

Dobe I see what you mean about entering a value into a program, I don’t use one myself so I never think of that use for efficiency.

If you come up lighter than you want you can boil some DME or sugar in a little water and add that to the fermentor.

I found out I get better efffiency from a better crush. crushing a litte finer has helped a lot .

barger,

I read on another thread that NB will give you a finer crush if you request it. I guess you would only need to do this if you don’t have your own mill.

Fortunetly I crush my own grain.