# Calculating SG from nutrition information - pear juice



## bcp (13/11/17)

Not sure how to calculate SG for pear juice from nutrition information. 

When I made the cider on sat, I measured the SG using my refractometer and it seemed ridiculously low - 1.017. I tried some store bought apple juice with my refractometer and it was 1.040. I realised later - duh - I hadn't shaken the tin of pear juice. I didn't use my hydrometer because it's only a small experimental batch of 4.25 litres and I didn't want to pour that much off if I had a refractometer. 

It's Goulburn Valley pear juice. 
Per 100ml - 
Carbohydrated (sic!) 12.5g; 
Sugars 9.4g.


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## Lyrebird_Cycles (13/11/17)

You can take it to be 12.5 oP as the small amounts of non-carbohydrates won't figure in your calculation anyway.


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## bcp (13/11/17)

Lyrebird_Cycles said:


> You can take it to be 12.5 oP as the small amounts of non-carbohydrates won't figure in your calculation anyway.


Excuse my ignorance, what's oP?
Then, plus the 9.4 sugars - are they treated the same?
Or do they mean that total carbs are 12.5 and sugars are 9.4 of this total?


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## bcp (13/11/17)

I didn't know the relationship to g/l of a substance to the SG.

So - I found this online calculator, if total carbs are 12.5g/100ml, and IF total carbs by weight is the same as total sugar by weight, then the SG must be 1.048. 
That's assuming that total carbs by weight is the same as the sugars. I think Lyrbird Circles is suggesting the difference is miniscule? Is this correct? Will the additional 3g of carbs be converted by the yeast to sugars, or are they potentially not convertible?


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## Lyrebird_Cycles (13/11/17)

oP = degrees Plato, the measure of wort concentration used by brewers. Very similar to degrees Brix, the measure of sugar concentration used by sugar refiners.

Since this guesswork anyway, I didn't both with the gravity correction.

The online calculator assumes all soluble solids are sugar. That isn't the case with pear juice.


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