Refractometer Calculators - NB vs Brewers vs Terrill

I just got a new refractometer and am trying to figure out how to use it. Unfortunately I did not read ahead and figure out a wort correction factor, however, regardless of that number I am getting some very strange differences between the NB calculator and Brewersfreind and Sean Terrill.

My OG reading was 13.8 Brix, which gives me an OG of 1.056 at 1.000 wort correction for the prefermentation calculators on all three sites. (That falls to 1.054 using a correction factor of 1.040).

My current reading is 5.0 Brix. NB gives me a current gravity of .998, while both BF and ST give me 1.006 using the 1.000 wort correction. Even if I take the wort correction up to 1.040, I still get 1.006.

Anyone know how to account for the differences between these calculators?

I guess I will take a hydrometer reading in a couple of days but I was hoping to avoid that (this is a 1 gallon batch).

If you need to use your hydrometer, you can probably (gently) drop it through the top of the jug instead of pulling a sample. Just make sure your sanitation is top notch.

fourfarthing said:

If you need to use your hydrometer, you can probably (gently) drop it through the top of the jug instead of pulling a sample. Just make sure your sanitation is top notch.

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Nah, the hydrometer is too long. It only goes about halfway down before it hits the bottom.

Unless you used wine yeast or Saison yeast (or were infected some how), I'd guess that the 1.006 is correct. either sanitize and drop in a hydrometer or pull a sample. At the end of ferment it's easier and more accurate to use a hydrometer anyway, and you can then start guesstimating a correction factor if you don't want to go through the process.

Odd about the NB calculator. Never used that one, but I do swear by their priming sugar calculator. But you are right about it being different.

You don't need to correct the first reading (without alcohol) but yes, if you only have a brix scale you need to convert. Also at the end if you keep getting the same reading you know fermentation is done. ABV well, that would be an estimated figure, but that is good enough for me.

Hoppy2bmerry said:

You don't need to correct the first reading (without alcohol) but yes, if you only have a brix scale you need to convert. Also at the end if you keep getting the same reading you know fermentation is done. ABV well, that would be an estimated figure, but that is good enough for me.

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Right, I am not overly worried about accuracy, just using the refractometer to tell me if it's done or not.

Still I am just curious as to how to explain the discrepancy in the calculators. I will check again in a few days, confirm with hydrometer sample, and declare a winner.

The yeast is cultured up dregs from Apex Predator, believed to be WY3726.

+1 for terrill.

Apex sounds pretty good right about now.

Any refractometer calculator gets thrown off by a wide variety of things. In particular there has been correlations between oil content from flaked oats/barley etc, as well as an SRM dependence (makes sense as the darker the liquid the more light absorption occurs. In addition, starch content and the composition of sugars will affect the wort correction factor as well.

If I care what the actual FG is, I'll use a FG hydrometer. All I usually care about is whether it's stable or not, and a refractometer works just fine for that.

Interesting. I just packaged a cider that I measured with the refractometer and checked with hydrometer. It started at 12.8 Brix (1.052 according to both calculators). It finished with a raw reading of 4.6 Brix. That adjust to a FG of .998 according to NB, 1.006 according to Terrill/Brewsfriend. Measured with the hydrometer and got .997.

I will check the farmhouse ale described in the first post next. I was more suspicious of the NB calculation coming out at .998 but now I am thinking that may actually be accurate.

Thanks guys!

Informative as always!

Aristotelian said:

Interesting. I just packaged a cider that I measured with the refractometer and checked with hydrometer. It started at 12.8 Brix (1.052 according to both calculators). It finished with a raw reading of 4.6 Brix. That adjust to a FG of .998 according to NB, 1.006 according to Terrill/Brewsfriend. Measured with the hydrometer and got .997.

I will check the farmhouse ale described in the first post next. I was more suspicious of the NB calculation coming out at .998 but now I am thinking that may actually be accurate.

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Cider is not the same as wort. I don't even know the right correction factor for cider but it appears it might be 0.999 or something like that, not 1.040.

So... NB is okay on the cider, but totally wrong on the beer, is my guess. I use Sean Terrill's calculator as it is clearly based on a lot of scientific research. Basis for NB, who knows. Brewer's Friend seems consistent with ST so that's cool.