# Pre boil grav

Now curius. About pre boil grav. And original grav. Whats the difference. Me aim for. For. Orginal grav at end of boil. But take a preboil grav reading as well

That depends on the boilâ€¦ Vigorous, and you can gain as much as 10-12 pointsâ€¦ Sneezles61
I used to look at that piece of the puzzle, but donâ€™t pay attention nowâ€¦ Using that grain bill equation I figured out, really gives me my answerâ€¦

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Pre boil gravity is necessary to calculate mash efficiency. If you care about numbersâ€¦

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I just look at the finished product efficiencyâ€¦ Therefore on a piece of paper I can build what I wantâ€¦ I know my system quite well and its very dependableâ€¦ Sneezles61

I like numbers

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Same. Iâ€™ve even found myself embracing algebra thanks to this hobbyâ€¦

Nope. If I hit my OG I donâ€™t really care about my mash efficiency. Plus if you know your system and hit your numbers then your pre boil OG should be close. I hate math.

Yea I hear ya. Same here. Plenty of brew days I havenâ€™t measured pH or taken any gravity readings at all. Followed my process and the beers turned out great. Consistent with past brewings even.

If one is a fail I like having all the data to go back and figure out why. Besides it only takes a few ounces of wort. I actually measure and record first runnings gravity as well. Maybe Iâ€™m anal.

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I always take my preboil SG. The mash efficiency is easy to figure from that, but the real reason is to figure out if Iâ€™m going to need to add some DME to hit my predicted OG.
But, I am obsessive about recording everything, even on recipes that Iâ€™ve done for years.

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Alright, so today is a brew day with a new grain bill from my mentor â€¦ Iâ€™ve done my math, and have the gravity figuredâ€¦ Iâ€™ll measure the final as I go into the fermenter â€¦ Testing myselfâ€¦ Weâ€™re doing a winter warmer dark wheatâ€¦ 15 gallon batch, set. ABV @ 6.9%â€¦ Im straying from my path!! Sneezles61

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Me brewing a tripplel at the BREWERY recipy all worked out on paper. Og 1.075

When I taught algebra I had a difficult time not explaining to the kid in back who asked, â€śWhen are we ever going to use this stuff?â€ť that it was essential to brewing beer.

And when I taught computer science I had to convince kids that if they couldnâ€™t calculate it with a pencil and paper, they probably wouldnâ€™t be able to do it with a computer!

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Me love to do math bye paper and pen than compare with software if i did right. Did not use math for long time. But now i moved to allgrain love this

This explains a lot for me.

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