

09022013, 01:58 AM

#1

Aug 2013
Posts: 480
Liked 120 Times on 74 Posts

For those who are just beginning to brew, figuring out how much wort is in one's kettle at any point in the boil is a simple mathematical exercise.
We start by calculating volume that the wort displaces in cubic inches. The formula for calculating the volume of wort in a cylinder is:
volume_of_wort_in_square_inches = 3.14 x the_radius_of_our_kettle_in_inches x the_radius_of_our_kettle_in_inches x the_height_of_our_wort_in_inches
For example, if we measure 8" of wort in a stockpot that has a diameter of 14", then the volume of the wort is 3.14 x 7 x 7 x 8 = 1,230 cubic inches.
Next, we have to convert cubic inches to gallons. There are 231 cubic inches in a gallon; therefore, we have 1,230 / 231 = 5.33 gallons of wort in our kettle.
As one can clearly see, one doesn't need a fancy sight gauge or markings on a pot to determine how much wort is in one's kettle. All one needs is a clean metal ruler and a calculator (use a sanitized metal ruler if the wort has already been chilled).



09022013, 02:02 AM

#2

Sep 2012
, Florida
Posts: 1,401
Liked 217 Times on 148 Posts

I just mark my spoon at 5, 6 and 7 gallon intervals. I don't need to be doing math on brew day!



09022013, 02:07 AM

#3

Aug 2011
Tiverton, Rhode Island
Posts: 11,387
Liked 1790 Times on 1467 Posts

Quote:
Originally Posted by masskrug
I just mark my spoon at 5, 6 and 7 gallon intervals. I don't need to be doing math on brew day!

^^^ This. I marked my mash paddle then switched pots so I made a dip stick. I measured out a gallon in a jug with a measuring cup. Filled a gallon, made a mark, added another gallon, made a mark, etc.



09022013, 02:09 AM

#4

Sep 2013
Fairfax, Virginia
Posts: 5
Liked 1 Times on 1 Posts

Quote:
Originally Posted by masskrug
I just mark my spoon at 5, 6 and 7 gallon intervals. I don't need to be doing math on brew day!

You made my day.. I am rolling on the floor



09022013, 02:53 AM

#5

Aug 2013
Posts: 480
Liked 120 Times on 74 Posts

Quote:
Originally Posted by masskrug
I just mark my spoon at 5, 6 and 7 gallon intervals. I don't need to be doing math on brew day!

That's what I did when I first started to brew. However, I switched over to using cubic inches after I started to brew different lengths of beer in differentsized kettles. I can run several calculations in the time that it takes to fill a kettle and mark a spoon.



09022013, 04:15 AM

#6

Aug 2011
Tiverton, Rhode Island
Posts: 11,387
Liked 1790 Times on 1467 Posts

Quote:
Originally Posted by EarlyAmateurZymurgist
That's what I did when I first started to brew. However, I switched over to using cubic inches after I started to brew different lengths of beer in differentsized kettles. I can run several calculations in the time that it takes to fill a kettle and mark a spoon.

True, but I always use the same pot so I did the fill and mark routine 1 1/2 years ago. It took about 15 minutes and now I never have to make any calculations. Just dip and look at the marks.



09022013, 11:32 AM

#7

Jun 2013
Sac of California, CA
Posts: 279
Liked 73 Times on 47 Posts

Ye olde spoonometerŪ. Calibrated with ye olde random "near a gallon" volumetric device.
You could make a plastic or wooden ruler in the shape of a spoon or paddle. You could even mark one side in fractions of an inch and the other in gallon and quart equivalents. Then when you drop your calculator in your wort, you can still brew
The first inch of my pot doesn't have the same volume as the rest of the inches. Anyone else have that problem
Now I need to go calculate how much longer my plastic spoon gets when it's hot. Hmmm. It grows about 10 times as much as a steel ruler which grows about four times as much as a wooden paddle. I guess we'd be better off with a wooden ruler. We could even do the calculations and mark it ahead of time. Wait a minute.
Seriously, this is a good alternate way to initially mark your measuring tool but it seems like unnecessary work to keep doing the math and not creating a direct measuring device. Besides that it allows the introduction of errors every time you have to calculate.



09022013, 11:52 AM

#8

mean old man
Oct 2012
Sterling, VA
Posts: 6,227
Liked 2175 Times on 1365 Posts

mine is easy. 30 qt pot is 15 inches tall, so 2 qts per inch
& I use an aluminum ruler.
x2 or /2 is not too much math for a brew day
__________________
"Beer. Good."  Words of House Grog
drinking: Otto M. Gourd Pumpkin Barleywine, Jewel Thieves Apple Wine, Fresh Squee Zed IPA  bottle conditioning: LoCo Foot Barleywine, Basque cider  lagering : Schwarzbier  fermenting: apple wine, Skeeter Pee  on deck: Grodziskie



09022013, 12:10 PM

#9

BIAB Expert Tailor
May 2007
Jersey Shore, New Jersey
Posts: 9,688
Liked 1456 Times on 1107 Posts

I have ONE mark on my mash paddle that is finished batch size, a 1/4 keg...I eyeball two plus inches above that for pre boil, and an inch or so above that for post boil to account for yeast cake, thermal shrinkage and losses to trub and hop debris.
Quote:
Originally Posted by EarlyAmateurZymurgist
However, I switched over to using cubic inches.....

Wow...measuring your brewing volumes to the 1/2 ounce.
This thread reminds me of the missing strawberries on the USS Caine...
Part 1 https://www.youtube.com/watch?v=1EO_8dDKTsU
Part 2 https://www.youtube.com/watch?v=U8LR2okL8YM



09042013, 01:27 AM

#10

Apr 2011
Houlton, ME
Posts: 1,800
Liked 534 Times on 366 Posts






