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 Home Brew Forums > Temp Correction Formula for Hydrometer
06-29-2006, 12:11 PM   #11
jcarson83
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http://http://www.hbd.org/brewery/li...mCorr0992.html

Theres where I got the formula if anyone is interested.
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06-29-2006, 01:50 PM   #12
Spyderturbo
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You have the wrong formula. Here is the correct one:

C = ((1.313454 - (0.132674*F) + (0.00205779 * F^2) - (0.000002627634 * F^2)))

Where F = Temperature in degrees Fahrenheit.

C = Correction

So,

CG = C + (SG * 0.001)

Where,

CG = Specific Gravity corrected for temperature

C = Correction from above forumla

SG = Specific Gravity before temperature correction.

Here it is for everone using Degrees Centigrade:

C = ((1.313454 - (0.132674 * ((C * 1.8) + 32)) + (0.00205779 * (((C * 1.8) + 32))^2)) - (0.111112627634 * (((C * 1.8) + 32))^3)))

Then continue with the formula above formula for CG

If you would like to use Excel for this, do the following:

Degrees F calculation

1) Use Cell B3 as your temperature (F) input.
2) Use Cell B5 as your SG input
3) Paste the following into Cell B7:

=1.313454 - (0.132674*B3) +( 0.002057793*(B3^2)) - (0.000002627634*(B3^3))

Paste the following into Cell B9:

=B5+(B7*0.001)

Cell B9 will contain your temperature corrected SG

For people using degrees centigrade, change the formula pasted into Cell B7 to the following:

=1.313454-(0.132674*((B3*1.8)+32))+(0.002057793*(((B3*1.8)+3 2)^2))-(0.000002627634*(((B3*1.8)+32)^3))

I'm sure that I could have reduced the formula down to something "prettier", but I really didn't feel like wasting time doing that. Besides, isn't that what's so nice about using Excel.

Cheers!

Disclaimer = It is possible that I made a transposition error when transferring this from Excel, so please check the Excel results against a table before using it.

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12-28-2006, 11:35 PM   #13
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Damn thanks man I was looking forever for this formula for my excel sheet. Thanks dude

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04-12-2009, 06:34 PM   #14
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i believe the original formula was supposed to be

Correction = 1.313454 - 0.132674*T + 2.057793e-3*T^2 - 2.627634e-6*T^3

but this assumes a hydrometer that is calibrated to 59F. if your hydrometer is calibrated to a different temp like 68F then i don't think this formula will not work. I've been looking for a formula that can be used for any calibration temp but so far haven't had much luck.

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09-04-2009, 02:20 PM   #15
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Quote:
 Originally Posted by TipsyDragon i believe the original formula was supposed to be Correction = 1.313454 - 0.132674*T + 2.057793e-3*T^2 - 2.627634e-6*T^3 but this assumes a hydrometer that is calibrated to 59F. if your hydrometer is calibrated to a different temp like 68F then i don't think this formula will not work. I've been looking for a formula that can be used for any calibration temp but so far haven't had much luck.

This is exactly the problem I am running in to. I am trying to create a set of calculators for mobile devices, phones and such. I have a few already working but can not seem to find the formula for the hydrometer that can be adjusted to different calibrations temps.

If there is any body out there better at math than I am they might be able to modify the above formula to include the calibration temp variable.
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09-07-2009, 09:40 PM   #16
kyral210
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Thanks for the formulae. However, there is a problem!

Old fashioned hydrometers are calaborated at 15°C, but modern ones are collaborated at 20°C. The equation given before is for 15°C hydrometers. What makes it worse is that nowhere on line says which the string of numbers mean, or where they come from, so I can't develop my own 20°C equation.

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11-17-2009, 11:00 PM   #17
Guido
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I found a formula that will do hydrometer corrections no matter what your hydrometer is calibrated for. Mine, which is about 20 year old, is pegged to 70 degrees instead of the more standard 59 degrees.

This is the formula for Microsoft Excel:

Code:
`=A1*((1.00130346-0.000134722124*A2+0.00000204052596*A2^2-0.00000000232820948*A2^3)/(1.00130346-0.000134722124*A3+0.00000204052596*A3^2-0.00000000232820948*A3^3))`
Easily, the longest formula I've EVER typed into a spreadsheet. At least it works. I've tested the results against hydrometer correction charts in "How to Brew", "Brewing Quality Beers", and "Brewing Lager Beer".

There are some assumptions you will need to know for that formula to make any sense. Do this:
2) Cell A1 will hold your measured Specific Gravity reading. Type in 1.050 for testing purposes.
3) Cell A2 will hold your measured temperature. Type in 120 (I'm assuming Fahrenheit) for testing purposes.
4) Cell A3 will hold your hydrometer's calibration temperature. Mine is 70, but you can type in 59 since that's probably what yours is.
5) Copy and paste the above formula into cell A4.

If you used the values, 1.050 (measured s.g.), 120 (measured temp), and 59 (calibration), then you should see 1.0610 for your calibrated specific gravity reading.

I'm building a spreadsheet to help me plan my beers and I'm willing to give it away for free if anyone can tell me how to post it to this Forum.

Cheers,
Guido
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11-18-2009, 10:09 AM   #18
kyral210
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I am thinking of building an open source home brewing and wine making calculator. What do you think?

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11-18-2009, 01:37 PM   #19
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03-08-2010, 07:51 PM   #20
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That Beer Recipator link is awesome thanks

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