[ccfoo242]

I'm a bit frustrated over differences in ways people convert refractometer readings to specific gravity.

I have a pre-fermentation reading of 12.9 brix which beersmith converted to 1.053 SG.
http://www.fermsoft.com/gravbrix.php lists 12.85 brix as 1.052, so its pretty close to beersmith.

Now I'm trying to use Sean Terril's site to convert a post-ferment brix reading into a final gravity.

I enter:
Original RI (°Bx):   12.9
Final RI (°Bx):   6.4

And it gives me this for results:
Original Gravity:   1.0501 (12.4°P)
Estimated Final Gravity:   1.0118 (3.01°P)
Alcohol by Volume:   4.9% (4% ABW)

Sooo....is 12.9 brix 1.050 or 1.053? I'm confused.    It looks like he divides the brix number by 1.04 to get degrees plato. I think I may have screwed up my configuration in Beersmith as it requires you to calibrate your refractometer...which I sort of fudged... So this may be all my fault.

[jmcamerlengo]

I use it. Its always the same as Beersmith for OG.

I dont have my config settings on me right now. I will check when I get home on my config settings!

[a10t2]

Sooo....is 12.9 brix 1.050 or 1.053?

12.9°Bx is 1.0522 (SG 20/20°C). A refractometer reading of 12.9°Bx *in wort* corresponds to an SG of about 1.049-1.051, depending on the wort correction factor.

This came up in a thread a few days ago: http://www.homebrewersassociation.org/forum/index.php?topic=11513.msg144017#msg144017

You'll have to scroll down until someone fixes the anchored URLs. Fifth post from the bottom.

[ccfoo242]

I'm making a starter this weekend so I'll use that as an opportunity to double check everything and fix my calibration in beersmith. I'm not sure where I got the numbers I put in there but my correction factor was something like 0.99.  When I put in some values that give me a correction closer to 1.04 then beersmith matches Sean's site for OG.

[a10t2]

Pre-fermentation, any calculator should give the same result as long as the wort correction factor is the same.

Post-fermentation, there's no comparison. My calculator's right, and everyone else's is wrong.

[ccfoo242]

Pre-fermentation, any calculator should give the same result as long as the wort correction factor is the same.

Post-fermentation, there's no comparison. My calculator's right, and everyone else's is wrong.

Hehe, I just noticed who you were...I'm slow that way! 

Yeah, I was using yours for post-fermentation...thanks for the site!

All of my confusion was due to the screwed up value I have in beersmith for the correction factor. Live and learn!