Bought a Refractometer...

[psujeeperman02]

So I was brewing a pale ale last weekend....while I was waiting for the wort to chill down, I was shopping on Amazon for a refractometer...
Excited that it'll arrive in 2 days, I completely forgot to take an OG reading. F!

Refractometer arrived. Will take a reading shortly...
Question is...will I be able to calculate what my OG was?
Is ABV calculation also out of the question at this point?

 

[cswis86]

You can estimate your OG will this calculator:

https://www.brewersfriend.com/allgrain-ogfg/

You should be able to get a pretty good estimate of you OG and then measure you FG to determine ABV.

 

[raysmithtx]

Refractometers cannot accurately measure anything with alcohol in it. You must use a chart to get accurate measurements once the fermentation has started. I use this one and have found it very accurate for my brewing.
http://seanterrill.com/2012/01/06/refractometer-calculator/

 

[MapleGroveAleworks]

So you have the item 2 days after brewing? OG will have dropped some, impossible to tell how much. You'll never have a perfectly reliable OG reading for this batch. Was it an all grain or extract batch? If extract, OG would be very consistent to whatever recipe you used. If all grain, all you can do is guesstimate. If you know your efficiency and what your system normally produces, it would be easy to estimate OG

 

[kh54s10]

Since it has been fermenting the refractometer will not give you an accurate number. The presence of alcohol skews the reading. There are calculators for making a correction but they are not totally accurate.

Was the pale ale an extract kit? If so, you used all the ingredients and ended up with the proper volume, the OG the kit called for will be very close.

If all grain, I doubt you will be able to know the OG or the ABV.

 

[NeoBrew]

This question gave me a thought. Since a refractometer is affected by alcohol, but you can correct for the alcohol by using a calculator. Couldn't you also take a FG reading with a hydrometer, then a FG reading with a refractometer, and then calculate the OG? Wouldn't this also be a way to estimate the alcohol content of a finished beer?

 

[day_trippr]

A 6% ABV beer could read the same on a hydrometer as 1.008 SG sugar water...

 

[NeoBrew]

A 6% ABV beer could read the same on a hydrometer as 1.008 SG sugar water...

Yes, of course the hydrometer would always read the SG. What I was wondering is if the error in the refractometer that was caused by the alcohol in the beer could be used to measure the deviation between the hydrometer and the refractometer. Then this deviation could be used to determine the alcohol content and possibly the OG.

 

[jrcrilly]

This question gave me a thought. Since a refractometer is affected by alcohol, but you can correct for the alcohol by using a calculator. Couldn't you also take a FG reading with a hydrometer, then a FG reading with a refractometer, and then calculate the OG? Wouldn't this also be a way to estimate the alcohol content of a finished beer?

Yes, that is what we do, using an online calculator. No problem. I will find and post the calculator we use.

It is the third calculator on this page: https://www.northernbrewer.com/learn/resources/refractometer-calculator/

 

[NeoBrew]

It turns out that Beersmith has a calculator exactly for this. Input refractometer reading in Brix, hydrometer reading in specific gravity and it estimates original gravity as well asl alcohol content.

 

[seatazzz]

Brewer's Friend has one as well. It's what I use if I'm fermenting in my carboy and don't want to break out the autosiphon to get a full hydrometer sample as I don't have a wine thief long enough.