Refractometer calculator

[alb]

For those with refractometers, so far they’ve only been accurate for pre-fermentation values. I’ve been using this conversion calculator for awhile and it seems to be pretty accurate for post-fermentation values. Try it if you dare.

http://www.northernbrewer.com/refractometer-calculator/

[Beer-lord]

Alb, do you check your OG on the refractometer with your hydrometer? If so, are they the same? My hydrometer is always higher by about .003 and both have been calibrated often and appear to be fine.
I've never bothered to check the gravity after fermentation but will give it a try this week just for shits and giggles.

[DaYooper]

Thanks Alb! I just picked one up during the AIH Black Friday sale. Was going to play with it last nite (finally have some time) but alas I dont have any distilled water. Need to pick some up tonite and will try to see how it compares with my hydrometer on my Peak's Pike IPA that is aging in the secondary. Perfect timing as always!

[Foothiller]

I get good use of a program on my iPhone called BrewCalc. Fairly simple functionality, but really useful for using the refractometer to calculate the SG at intervals during fermentation. It adjusts for alcohol content impacts on the readings, has a couple of other features, and is inexpensive.

[jimjohson]

I just finished experimenting and, the converter shown, will not give me accurate information just entering gravity readings. Ok, I'm not the sharpest tack in the box so I got a couple of questions.

1) Do y'all's have 2 scales, brix and gravity showing?
2) (assuming yes to #1) Is this to imply that the gravity side is inaccurate, so the brix must be used to get the alcohol % correct? Got to say it seems to read the same as my hydrometer. Actually better I always feel like there is a + or - in reading the hydrometer.

[FedoraDave]

Alb, do you check your OG on the refractometer with your hydrometer? If so, are they the same? My hydrometer is always higher by about .003 and both have been calibrated often and appear to be fine.
I've never bothered to check the gravity after fermentation but will give it a try this week just for shits and giggles.

0.003 is barely a blip on the radar, though. I mean, I'd call that pretty much a match, considering we're doing this stuff in our kitchens and spare closets.

[Beer-lord]

Agreed Dave and since I use the hydrometer for the FG, I use it for the OG too but the refractometer comes in very handy to check pre-boil gravity as well as during the boil to make sure I'm going to be in the ballpark.

[FedoraDave]

Never checked pre-boil gravity, and I'm not even sure what it would indicate. I'm sure a lot would depend on temperature, too, and that can vary wildly.

[Beer-lord]

That's the great thing about the refractometer, the decent ones have Auto Temperature Compensation so you don't have to worry about temps. You only need a very small amount too.
Checking pre-boil isn't a real big deal for me but I like to see how close I'm coming to the projected Beersmith and many use it instead of iodine to make sure the mash has converted well.

[braukasper]

For those of you with Beersmith you have that calculator included. Some recipes will give a preboil gravity. That helps in knowing that collected enough wort.

[Crazy Climber]

For anyone who wants to get further into the nuts and bolts of refractometer readings, there’s this link.
Sean Terrill has done a lot of work on building a better mousetrap when it comes to converting refractometer readings to gravity readings. I find his formula to be superior to anything else I’ve found out there, from an accuracy standpoint. The link above brings you to his simple OG/FG calculator. There’s links in his description at the top of the page to a more-detailed explanation of his methodology, and also a link to a spreadsheet that you can download and use, to track refractometer and hydrometer readings for multiple batches.
I use his spreadsheet, and by tweaking the wort correction factor based on experience, you can really dial in the refractometer readings to a high degree of confidence.

( PS to Dave: Pre-boil gravity can tell you when you've got enough wort as Bob noted, or if you collect a known amount, it will tell you your mash efficiency, which can be helpful for future recipe formulation.)

[alb]

That spreadsheet is awesome!