Efficiency Calculations

[traviswalken]

I am new to brewing and want to make sure I am calculating and using efficiency calcs correctly. Please check my math & logic:

10 lbs of 2-row with a gravity of 1.036 = 360 points

If I brew a 5.5 gallon batch with this grain bill, my maximum specific gravity will by calculated like this: 1 + (360 points / 5.5 gallons / 1000) = 1.0655

After cooling my wart, if I hit my volume target (5.5 gallons) and get a gravity reading of 1.05, I calculate efficiency like this: (1.05 actual gravity - 1) / (1.0655 potential gravity - 1) = 76.3%

Am I on the right track?

Thanks in advance for the help!

 

[lumpher]

your logic and math are perfect. use that formula (or beersmith), and you're doing good

 

[traviswalken]

Okay.

My next question is about how to use this on brew day.

Let's say the simple recipe I describe above has a target OG of 1.049 (75% efficiency). Let's assume I will boil off 1 gallon per hour for 1 hour.

Therefore, I am targeting preboil gravity like this: 1 + (.75 efficency x 360 points / 6.5 gallons / 1000) = 1.042

Let's say I actually have 6.5 gallons preboil and get a gravity reading of 1.055. This would indicate I can fix the "problem" by adding some water. Or if the opposite occurrs, I can add some boil time prior to my first hop addition to get rid of some water.

Is this correct?

I wouldn't think it would be worth modifying hop additions to compensate for more or less wort.

 

[kylevester]

Hop efficiency begins to decline at gravities over 1.050.

Yes, you could "fix the problem" by adding water, but only such that you end up with a final OG of 1.049 +/- 0.002. If you add water and boil down to 5.5 gallons, you don't change anything. So, if you want to hit the OG, then dilute and you'll end up with more beer. Or, don't sweat it, call it an imperial, add a little more hops, and have yourself a powerful brew. I've done that a couple times when I get insanely high efficiency for reasons I can't explain.

 

[traviswalken]

Thanks for the help.

I updated my brew spreadsheet preboil volume, preboil gravity, anticipated post boil gravity, water correction volumes, flux capacitor capacity, etc.

What I have learned more than anything else is that I am a total beer geek. :rockin:

 

[FuzzeWuzze]

Thanks for the help.

I updated my brew spreadsheet preboil volume, preboil gravity, anticipated post boil gravity, water correction volumes, flux capacitor capacity, etc.

What I have learned more than anything else is that I am a total beer geek. :rockin:

Spend the $25 and get Beersmith then. Or just go grab it for the 21 day trial..you'll want it.

 

[traviswalken]

Spend the $25 and get Beersmith then. Or just go grab it for the 21 day trial..you'll want it.

Thanks for the advice. I downloaded the trial version a couple weeks ago. I like it and will purchase it at some point.

I am doing my own calculations to start with so I will understand how brewing (and beersmith) works.