Condensed Steps for Brew Day Measurements

[Monmouth00]

Beersmith says that’s 37.3% attenuation. But the ABV is right on target for the recipe.
Do I still have something to worry about?

 

[DBhomebrew]

26/50 is .52

Punching those numbers into the Brewer's Friend ABV calculator gives 3.25%ABV standard.

 

[Monmouth00]

Yeah, I got that too once I realigned the numbers.
Any ideas what went wrong?

 

[Monmouth00]

Using the Brix calculator, my OG was 12.4, and my final was 6.6.
That’s supposed to be 5.1% ABV.
I’m very confused.

 

[DBhomebrew]

When you took your gravities, did you read the refractometer in Brix and use the calculator to get specific gravity? If not, your numbers are on a foundation of sand.

 

[DBhomebrew]

Using the Brix calculator, my OG was 12.4, and my final was 6.6.
That’s supposed to be 5.1% ABV.
I’m very confused.

Well, there you go!

Put those into the Brewer's Friend calculator with an assumed 1.04 wort correction...

1.048
1.012
4.86%

 

[DBhomebrew]

You can go down a rabbit hole about different calculators and approaches to these numbers.

1.050/5.1% from one calculator and 1.048/4.8% from another is totally expected.

I'd record your Beersmith numbers for each batch as well as Brewer's Friend's. Over a few batches you'll find you'll gain the ability to predict how things turn out.

For my purposes, finding consistency and predictability is much more important than accuracy.

ETA: I checked Brewer's Friend without the wort correction and it came back as agreeing with your 1.050 from Beersmith. That wort correction factor adjusts for the complex sugar types found in wort.

 

[Monmouth00]

When I look into my refractometer I see this:

When taking my measurements, why wouldn't I look at my SG side, instead of looking at Brix then converting?

My OG was 1.050 (12.4 Brix) and my FG was 1.026 (6.6 Brix)

Why does it show both when I should only be looking at Brix?

Calculating by the SG gives me 3.2% while the Brix calculator gives me 5.06%

So you're saying I should only go by the Brix and not the SG?

Can you explain why? Like I'm a 4 year old, please, because I'm very very confused.

 

[DBhomebrew]

A refractometer measures the refraction of light through a sugar solution. This is measured in Brix or Plato, interchangeable for our purposes.

With a simple sugar solution, the SG scale they helpfully provide is usable. But, we brewers don't deal in simple sugars. We've got things like maltose in there as well. 1.04 is a common default correction factor for beer wort.

All's well and good for pre-fermentation. Once alcohol joins the party, it starts to skew the light making it appear to be a higher concentration of sugar. The calculators account for this. Knowing the OG and apparent current SG in Bx, the calculator figures out the true sugar concentration. The SG scale on the refractometer doesn't have any idea it's being tricked by the alcohol.

Takeaway:

Refractometers measure simple sugar water solutions in Brix. The SG scale assumes this simple sugar water solution.

Calculators can compensate for the presence of complex sugars and alcohol.

Measure and record in Brix. Convert to SG.

 

[Monmouth00]

Thank you. I was getting very very frustrated thinking I screwed something up.
Your explanation is soothing, and is greatly appreciated!!

 

[DBhomebrew]

I'm a big fan of using a refractometer. As with all things, understanding the tool does wonders.

Do look into best practices for sample collection, etc. Mixing up the wort before pulling the sample, letting the sample settle before putting it on the lens, temperature awareness, etc.

I like to take 3 separate readings of each sample and average them before inputting into the calculator. Over a few batches I've found that each sample set has gotten tighter as my technique improves.