how to add Sauvignon Blanc grape concentrate

I am at a total loss on how to add this to a recipe 46 oz Alexander’s Sauvignon Blanc grape concentrate (add at end of boil).  I contacted Northern Brewer and they did not have an answer.  I can measure the brix but how do I get a value that Beersmith 2 can use to give me what my SG will be??

Thanks Much
~~ Bob

This calculator will get you from Brix to SG. 
The formula it uses is:  SG = (Brix / (258.6-((Brix / 258.2)*227.1))) + 1

From there, you can get the "potential" (the value you'd enter into BeerSmith) of the concentrate by the following:
Potential = (Solution Volume * Extract SG ) / Extract weight

Thanks mm658  will give it a go!!  Will be brewing this next week.  I used the fruit add on from BS2 and came close to what the OG is on the recipe sheet.  I am thinking of adding a extra pound of pils to ensure I hit it.

Hi, Bob. I'm brewing Northern Brewer's Antithesis AG with the same concentrate and have run into the same problem that you had: I don't know how to add it to Beersmith. Can you give me your calculation? Thanks in advance.

-Doug

Doug I just ended up adding it.  Guess what hit Northern's number right on the head.  I did not brew this till a month ago.  some health issues got in the way.

Any fermentable potential in BeerSmith has to be expressed as a ratio of 1 lb to 1 gallon.  As weight units that's a ratio of 1:8.33, which converts it to metric. Specific gravity is dimensionless, but that's the math for breaking down juices and concentrates for beer recipes.

So, you simply take the specific gravity or brix measurement and divide by 8.33 to get extract potential. 

Alexander's lists their Sauv Blanc extract at 68 brix.
68 / 8.33 = 8.16 brix = 1.0325 sg. of 1 lb concentrate in 1 gallon of water.

Easy.