Hydrometer and alcoholmeter temperature correction forumlae

[TwoSheds]

Hi all, I know there are a slew of online and offline programs for correcting gravity on a hydrometer or proof/tralle on a alcoholmeter, but I'd really like to work these into my spreadsheet that I take notes in. Does anyone have some reasonably succinct formulas for these? Bonus points if it's in or nearly in Excel style.

I've been using the one below for hydrometer but have a feeling it's not quite right.

B39×((1.00130346−0.000134722124×C39+0.00000204052596×C39^2−0.00000000232820948×C39^3)÷(1.00130346−0.000134722124×60+0.00000204052596×60^2−0.00000000232820948×60^3))

B39 is my gravity reading, C39 is my temp in F, and 60 is what my hydrometer is calibrated to.

Lots of pages will do the math, but not many mention the formula they use and I don't see these in the Calculators section on this site.

Thanks.

TwoSheds

[higgins]

That is the formula used by at least 2 calculators that I looked at.
Here is what I found at this link: Vinolab

The hydrometer temperatre correction for SG is performed with this expression:

corrected-reading = r * ((1.00130346 - (0.000134722124 * t) + (0.00000204052596 * t2) - (0.00000000232820948 * t3)) / (1.00130346 - (0.000134722124 * c) + (0.00000204052596 * c2) - (0.00000000232820948 * c3)))

Where:
r = reading
c = calibration temperature

What is it that makes you think it is 'not quite right'?

[Kareltje]

Funny: I saw the same question on a forum in my country, with exactly the same formula. Probably derived from HD.
The conclusion was, that the correction could be ignored.
This formula is clearly a transformation of a graph by a calculating system, something like the Fourier-transformation. I do not know the technique, but recognize it.

This techniques are simply arithmetic, just techniques.
Maybe that is why you think it is not quite right: has nothing to do with real relationships of density and temperature.

[TwoSheds]

What is it that makes you think it is 'not quite right'?

I had a couple readings that adjusted showed a rise in corrected gravity with a drop in temp, but it was probably a reading error.

I still haven't seen a formula for the proof/tralles scale. Anyone have one?

[Salt Must Flow]

What is it that makes you think it is 'not quite right'?

I had a couple readings that adjusted showed a rise in corrected gravity with a drop in temp, but it was probably a reading error.

I still haven't seen a formula for the proof/tralles scale. Anyone have one?

There's a chart shown on this page. It isn't hard to derive a formula from the chart. 1% ABV for every degree F. I've been going by that.