When is a gallon not a gallon? - Home Brew Forums

 Home Brew Forums > When is a gallon not a gallon?

04-11-2011, 12:19 AM   #1
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Jun 2008
Posts: 46

I am confused. I used an empty milk container as a measure for a gallon and it comes out 1/3 of a cup short even when filled to the top. The milk container states 1-us gallon or 3.78 litres. I used a liquid measuring cup for the measurment. So I went back to the store and bought a plastic pitcher that has a one gallon mark on it. It measures out the same as the gallon of milk-short 1/3rd of a cup?

What is anyone else using for a one gallon measure that is accurate?
Any help is appreciated....cheers

04-11-2011, 12:23 AM   #2
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Sep 2010
Tampa, FL
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I have a 1/2 gallon measuring cup. But now I use anything I have free to measure the depth of liquid in my brewpot. I made a spreadsheet relating depth of water and volume for my brewpot and so now all I have to do is measure depth. So I can avoid pouring 1/2 gallon after 1/2 gallon.

Of course there is also the 4% volume difference between water at varying temperatures...

04-11-2011, 12:26 AM   #3
dirtylarry
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Nov 2010
Hermitage, TN
Posts: 25

Weigh your water. 8# is a gallon.

04-11-2011, 12:45 AM   #4
DeafSmith

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Jan 2009
Richardson, TX
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Quote:
 Originally Posted by dirtylarry Weigh your water. 8# is a gallon.
8.33 pounds per gallon at room temperature, 8 pounds per gallon at boiling, or about 8.15 pounds per gallon at mash temperature.

04-11-2011, 12:52 AM   #5
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Jun 2008
Posts: 46

So I googled a gallon of water and found weights by water temperature and such, but I am still confused because a gallon of milk is still short 1/3rd of a cup when I use the same temp water. Also my brew pails are marked at 1,2,3,4,5 gallons and they all come up short when you fill it by using a milk container! I am using a liquid quart measuring vesel.I guess the important thing is to use the same container for all brewing and adjust your recipe's accordingly!

04-11-2011, 01:11 AM   #6
Malstorme
Yeast-herder

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Apr 2011
Sapulpa, OK
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Quote:
 Originally Posted by mnpaddler ..an empty milk container as a measure for a gallon and it comes out 1/3 of a cup short...
I'm sure my precision leaves something to be desired, but I pretty much don't measure anything in my batches that precisely. I prefer the RDWHAHB approach. If you're into anal precision (I understand, I am about somethings) a gallon contains 16 cups, so being a third of a cup short's not likely to ruin a batch of your current project (it's only a little over 2% off).

As to the recommendations about weighing, buying other items I'd say screw that. The point of measuring is to obtain known quantities. If your milk jug is 1/3 cup short, add the difference to your pot/carboy etc. I couldn't see buying something (especially not dragging out a scale and temperature conversion matrix chart!) when the FREE jug on hand does the job.

Your mileage may vary, but I'd suggest simply relaxing about it. Add the excess manually if it worries you. Or buy something more precise if you've got the money to spend.

I've never calibrated my equipment because for what I've done so far, "ball park" is close enough and has allowed me to replicate (at least to my amateur palate) what I've tried to.

Mals

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04-11-2011, 01:22 AM   #7
windbreaker123
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Mar 2011
bfe, oh
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Your question is weight v/s volume. 1 cup sand -1cup flour-1 cup sugar will all weigh differently. And depending on the time of year they will also vary. 1 Gal in weight is 128 oz. But when you add anything to the water. Per say weighing wort it will be heavier. So if you wanting to get close you would only consider volume not weight.

04-11-2011, 01:23 AM   #8
Yooper
Ale's What Cures You!

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Jun 2006
UP of Michigan, Winter Texan
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1 gallon= 128 liquid ounces= 4 quarts. If you're getting shorted by your milk producer, let them know. Or double check your liquid measuring cup, as that is the one that seems to be off.
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04-11-2011, 01:26 AM   #9
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Sep 2010
Tampa, FL
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The markings on the pails are WAY off. The gallon jugs you buy could be anything - don't trust them.

If you want to be exact, there are several options. If you want to go with the flow, estimates are fine too. Find something that works for you but don't trust market-bought gallons or arbitrary markings on pails - just an FYI my markings were all off by 1/4 to 1/3 gallon.

04-11-2011, 01:32 AM   #10
windbreaker123
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Mar 2011
bfe, oh
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Also milk containers hold and are capped most times with more than one gallon.