Brix to Gravity conversion

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JeffWScott

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Hey guys, there is something I'm just not getting.

I measured my Brix using a refractometer and got 12 before fermentation and 5.5 after.

If I use this calculator:

https://www.northernbrewer.com/learn/resources/refractometer-calculator/

I can covert each of these to SG so I get

12 Brix = 1.048 SG
5.5 Brix = 1.022 SG

So I'm like OH CRAP I didn't attenuate properly.

But if I use the next calculator on that page and punch in both numbers it tells my my FG is 1.005; which means I attenuated way more than what the SG is above.

I'm just confused how I'm supposed to be measuring this.

Any help would be amazing,

Thanks!
 
A refractometer won't work correctly after fermentation. The alcohol in it skews the results. You need to still use a hydrometer.

A refractometer will only give a good reading before fermentation. If you use it for after fermentation you have to put it in a calculator for it to do a conversion to get the FG. So, yes your FG is 1.005 with the numbers you provided.
 
TDB has it right. But Ive found that the NorthernBrewer site tends to end a little low for their calcs. I like the brewers friend one (ultimately I use a hydrometer, but if I was in a pinch...) which lands you at 1.010
 
I use a refractometer for small batches when I don't want to pull a sample. I agree, I get lots of variation depending on the calculator used. I did a test with a hydrometer to confirm and it looked like NB was best...
https://www.homebrewtalk.com/showthread.php?t=585678

However, I put your numbers into the NB calculator (middle on on the screen, "Brix to Gravity, during and after fermentation") and it comes up with 1.005.

Either way, the refractometer can at least tell you that the gravity is stable. You just have to trust your yeast that it attenuated to where it should.
 
I use a refractometer for small batches when I don't want to pull a sample. I agree, I get lots of variation depending on the calculator used. I did a test with a hydrometer to confirm and it looked like NB was best...
https://www.homebrewtalk.com/showthread.php?t=585678

However, I put your numbers into the NB calculator (middle on on the screen, "Brix to Gravity, during and after fermentation") and it comes up with 1.005.

Either way, the refractometer can at least tell you that the gravity is stable. You just have to trust your yeast that it attenuated to where it should.

Interesting. Like I said, Ive always felt like NB's was a little low. That being said... Im kegging a batch on saturday. Looks like a good opportunity to do a little experimenting with the hydrometer, refractometer and webs calcs
 
This is the one I use. I checked three brews with my hydrometer against the 'adjusted' refractometer and they were withing .001 of each other in the FG. Close enough for me. I don't use a hydrometer any more, just my refractometer and Sean's site.

I'm using my refractometer more and more now these days after just getting one last year. I find the adjusted readings to be within 0.001-0.002 versus the hydrometer, which is close enough for me as well. Does it *really* matter if the ABV is 5.7% vs. 5.8% anyway? Ha. Even hydrometers are barely accurate enough to discern that difference, much less our taste buds and "mouth-feel"ing nervous system.
 
I'm using my refractometer more and more now these days after just getting one last year. I find the adjusted readings to be within 0.001-0.002 versus the hydrometer, which is close enough for me as well. Does it *really* matter if the ABV is 5.7% vs. 5.8% anyway? Ha. Even hydrometers are barely accurate enough to discern that difference, much less our taste buds and "mouth-feel"ing nervous system.

In all honesty, half the time I don't even take readings at all...beer is beer. When I first started brewing I was all about.
 
To answer OP's question, to use a refractometer after fermentation, you also need to know the starting Brix or OG.

The first calculator on that link assumes there is no alcohol in the wort (before fermenting).

The second calculator is what you want to use which uses the starting Brix to estimate a correction due to the alcohol, then gives the final gravity using the correction.

But as others said, their calculator doesn't seem that good.
 
Someone earlier mentioned the one on Brewers Friend. I use that one. I have to admit I'm not terribly worried about getting an exactly perfect number, but it's easy to use, and I feel comfortable with it as the results I get seem to come very close to what the recipe specifies.
 
Someone earlier mentioned the one on Brewers Friend. I use that one. I have to admit I'm not terribly worried about getting an exactly perfect number, but it's easy to use, and I feel comfortable with it as the results I get seem to come very close to what the recipe specifies.

Yes, I believe that one uses the same formulae but obviously now I can't compare. You do need to make sure you enter the wort correction factor as 1.04 for accuracy or it won't work right.

I'm surprised Sean's site is down, it worked just fine a week or two ago. He'll probably get it back up soon. Maybe hurricane related?!
 
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