Calculating alcohol content from SG / Temparature

...calibrated at 20C

This was discussed at length only on 8 October and et seq.

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""From: "Matt Lyndon" Subject: Work out percentage alcohol (please help) Date: 08 October 2004 21:32

Hi all,

Just made my first batch of wine. Can somebody please offer some advice. If I know the starting gravity (1080) and I know the final gravity (992) what is the equation to work out the percentage alcohol. I read somewhere that you divide by a certain figure. Can anyone help. I am making Beaverdale Red Rioja.

Many thanks

Matt ""

I have looked through that (very long) topic but it does not answer my question.

It is not the calculation for abv from SG drop that I am after. It is the calculation that takes your SG reading and the temparature to give an adjusted reading.

Anyone help?

Here's an on-line calculator for the correction:

Thanks Ed, i will try to reverse engineer it.

I'll e-mail a spreadsheet to you directly that's already done - hope it helps.

Ed

1)These is the formula I used in producing my own Hydrometer Tables (with M. Excel). There are others available but this works for me! Potential Alcohol (%) = (Brix-2.5) * SG * 0.59 where Brix = ((SG-1) * 220.5) + 1.6

2)In Duncan and Acton's "Progressive Winemaking" you find: Potential Alcohol (%) = (Go - Gf) / F where Go is original gravity and Gf is final gravity, and gravity is defined as G = (SG-1)*1000. F is a value that takes into account the non fermentable solids in the must and is defined as F = 7.75 - 3*(Go

- 7) / 800

3) Temperature corrections may not be that significant in order to calculate the final alcohol content of the wine, however:

Temperature of Must oC oF hydrometer reading correction

5 42 subtract 0.002 10 50 subtract 0.001 15 59 no correction necessary 20 68 add 0.001 25 25 add 0.002

I hope this is what you were looking for. Cheers, Giovanni.

R-D-C wrote:

Spot on, thanks!