Author Topic: metric nerdery please: calculation question  (Read 3818 times)

Offline pikelakehomebrew

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metric nerdery please: calculation question
« on: March 22, 2012, 12:29:16 PM »
So I'm considering going metric with my calculations and measurements, and am presently reading an excellent book [Designing Great Beers by Ray Daniels]; and in his book he talks about calculating the malt bill for your recipe based on a few variables.  All his calculations revolve around Gravity Units (GU) and imperial measurements (pounds and gallons).  Like a couple sample formulas:

Code: [Select]
G.U. + Batch Size in Gallons = Total G.U.
Code: [Select]
G.U. per Pounds of Malt ÷ Extract Potential G.U. ÷ Mash Efficiency = Pounds of Grain Needed
Now I know the simple method to make this Metric-friendly would be to simply insert the formula for imperial to metric conversion right in the formula.  But I'm just curious, with formulas like this in mind, how does the REST of the world calculate things like Total Gravity, Pounds of Grist needed, etc.  Like would they just use °Plato instead or do they have entirely different formulas?

Just curious.
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Offline gmac

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Re: metric nerdery please: calculation question
« Reply #1 on: March 22, 2012, 12:34:14 PM »
I use Ibrewmaster and set the default settings to metric. 

My advice, if you do it in metric, stay in metric and don't try to switch back and forth in your head.  I was in school during the switch so I can sort of do both but I find that I often measure my hops in grams, my water in liters but my grain in lbs.  Not sure why. 

Offline nateo

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Re: metric nerdery please: calculation question
« Reply #2 on: March 22, 2012, 12:46:12 PM »
I'm pretty sure most of the probrewer world uses Plato, and wine guys use Brix.

The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.
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Re: metric nerdery please: calculation question
« Reply #3 on: March 22, 2012, 01:02:17 PM »
I'm pretty sure most of the probrewer world uses Plato, and wine guys use Brix.

The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.

48
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Offline weithman5

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Re: metric nerdery please: calculation question
« Reply #4 on: March 22, 2012, 01:05:58 PM »
I'm pretty sure most of the probrewer world uses Plato, and wine guys use Brix.

The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.

48.  thought it would take me all day to save a life. 8)
i use ibrewmaster and love it. i do everything in imperial units except for my hops.  i brew 2 gallons (about 8liters nateo :o) and it is easier to make the hops in grams.  i have been thinking of switching to metric before i got ibrewmaster but all i need to do is switch the default and it does it for me.

to the op instead of gravity points per pound, say a malt gives you 36 gravity points per pound.  you could divide this by 2.2 to get gravity points per kg and that would still be in a gallon. (now about 17 points per kilogram per gallon.  now divide by 3.9 so about 4.3 points per kilogram per liter.)  thus divide your potential by 12.5 and there you have it. 

now you see why i just let the ibrewmaster do it these days.
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Offline weithman5

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Re: metric nerdery please: calculation question
« Reply #5 on: March 22, 2012, 01:08:28 PM »
morti you beat me to it

sorry that was not 12 .5 but about 8.6
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Re: metric nerdery please: calculation question
« Reply #6 on: March 22, 2012, 01:34:27 PM »
I'm pretty sure most of the probrewer world uses Plato, and wine guys use Brix.

The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.

48.  thought it would take me all day to save a life. 8)
i use ibrewmaster and love it. i do everything in imperial units except for my hops.  i brew 2 gallons (about 8liters nateo :o) and it is easier to make the hops in grams.  i have been thinking of switching to metric before i got ibrewmaster but all i need to do is switch the default and it does it for me.

to the op instead of gravity points per pound, say a malt gives you 36 gravity points per pound.  you could divide this by 2.2 to get gravity points per kg and that would still be in a gallon. (now about 17 points per kilogram per gallon.  now divide by 3.9 so about 4.3 points per kilogram per liter.)  thus divide your potential by 12.5 and there you have it. 

now you see why i just let the ibrewmaster do it these days.

Lbs to Kilo would multiply by 2.2 rather than divide. 36 points per pound would be 72.72 points per kilo
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Offline weithman5

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Re: metric nerdery please: calculation question
« Reply #7 on: March 22, 2012, 01:39:48 PM »
22 pound kid only weighs 10 pounds.  ( 1 pound loaf of bread is 454 grams or just under a half pound)
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Offline a10t2

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Re: metric nerdery please: calculation question
« Reply #8 on: March 22, 2012, 01:53:36 PM »
But I'm just curious, with formulas like this in mind, how does the REST of the world calculate things like Total Gravity, Pounds of Grist needed, etc.  Like would they just use °Plato instead or do they have entirely different formulas?

The formula is actually the same, it's just the constants and units that change. So instead of representing potential extract as, say, point-gallons per pound, you'd use degree Plato-liters per kilogram, and so on. Base malts tend to be around 37 point-gal/lb, which is about 77 °P-L/kg. If you want to brew 20 L of a 12°P (1.048) beer at 80% efficiency:

(20 L * 12°P)/(77°P-L/kg * 80%) = 3.9 kg

or in American customary units: (5.25 gal * 48 points)/(37 point-gal/lb * 80%) = 8.5 lb

The two answers are the same, just given in different units.

°Plato tends to be more common in Europe, SG in the UK, and American brewers use whichever they learned first, more or less.

The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.

The real problem with the "imperial system" is that unless you specify which "pint" and which "ounce" you're talking about, you can't even come up with an answer.
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Offline punatic

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Re: metric nerdery please: calculation question
« Reply #9 on: March 22, 2012, 03:10:35 PM »
I find my brews taste superior if I measure my mash, ferment, and serving temps in Kelvins.   :o
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Re: metric nerdery please: calculation question
« Reply #10 on: March 22, 2012, 03:12:22 PM »
I find my brews taste superior if I measure my mash, ferment, and serving temps in Kelvins.   :o

nah, I don't drink beer if it's colder than 439 degrees.
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Re: metric nerdery please: calculation question
« Reply #11 on: March 22, 2012, 03:15:46 PM »
I find my brews taste superior if I measure my mash, ferment, and serving temps in Kelvins.   :o

nah, I don't drink beer if it's colder than 439 degrees.

439 degrees what  ::)
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Re: metric nerdery please: calculation question
« Reply #12 on: March 22, 2012, 03:21:23 PM »
I find my brews taste superior if I measure my mash, ferment, and serving temps in Kelvins.   :o

nah, I don't drink beer if it's colder than 439 degrees.

439 degrees what  ::)

439 degrees of separation!  (7 2/3 radians)
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Re: metric nerdery please: calculation question
« Reply #13 on: March 22, 2012, 03:26:53 PM »
I find my brews taste superior if I measure my mash, ferment, and serving temps in Kelvins.   :o

nah, I don't drink beer if it's colder than 439 degrees.

439 degrees what  ::)

okay, after further research I don't like my beer any colder than 280 degrees kelvin
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Re: metric nerdery please: calculation question
« Reply #14 on: March 22, 2012, 03:27:51 PM »
okay, after further research I don't like my beer any colder than 280 degrees kelvin

After still further research you will learn that that isn't a unit of measurement. ;)
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