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If I want to convert my specific gravity reading from one temperature to an equivalent specific gravity at 60F how do I do it?

Can you give me a correction factor for this case?

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3 Answers 3

All temperatures are in expressed in degrees F.

correction = 1.313454 - 0.132674*F + 0.002057793*F*F - 0.000002627634*F*F*F
SG_corrected = SG + (correction * 0.001)
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jsled's answer is for when you are using a hydrometer calibrated to 59 degrees F.

The formula to correct a reading for any hydrometer calibration temperature is as follows:

cg = corrected gravity
mg = measured gravity
tr = temperature at time of reading
tc = calibration temperature of hydrometer

cg = mg * ((1.00130346 - 0.000134722124 * tr + 0.00000204052596 * tr2 - 0.00000000232820948 * tr3) / (1.00130346 - 0.000134722124 * tc + 0.00000204052596 * tc2 - 0.00000000232820948 * tc3))

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I'm not sure if it's implemented on all of the StackExchange sites, but I believe at least the math ones support TeX or LaTeX markup: en.wikipedia.org/wiki/LaTeX –  theraccoonbrew May 2 '11 at 15:27
    
Not sure if its supported, so I added <sup> tags around the exponents in the code block. Still its a nasty formula to read w/out better formatting. –  tomcocca May 2 '11 at 20:14

You can also use a correction table like the one HERE.

You just add or subtract the difference from 1.000 at 60 with the temp you are at.

I hate quoting John Palmer, but he also has a table in Appendix A of Hot to brew.

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Why do you hate quoting John Palmer? –  Dustin Rasener May 2 '11 at 0:56

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