Hydrometer VS Refractometer

[MasterTheBrew]

So I hear that refractometers are more accurate to take OG readings and that after fermentation Hydrometers are more accurate with higher alcohol contents. I was wondering if anyone has anymore Info on this? I just took a reading of my beer that has been in the primary for 6 days and the Hydrometer reading was 1.010 and the Refractometer was 1.025... Big difference..

 

[Yooper]

So I hear that refractometers are more accurate to take OG readings and that after fermentation Hydrometers are more accurate with higher alcohol contents. I was wondering if anyone has anymore Info on this? I just took a reading of my beer that has been in the primary for 6 days and the Hydrometer reading was 1.010 and the Refractometer was 1.025... Big difference..

A refractometer measures the refraction of light. Alcohol skews this, so the reading is useless once alcohol is in the mix. The hydrometer reading would be the correct reading if fermentation has started.

There are some correction software tables available that attempt to help with the corrections, but none I've found are accurate. I have found that Sean Terrell's (spelling might not be correct) is the closest, but not 100% accurate.

 

[Spinout]

will the refractometer be off by the same amount w/ alcohol? if samples are taken consecutive days to determine if fermenting is complete, will it read the same if it is complete? or will 3 samples give 3 diff results even if the alcohol level is the same?

 

[Riot]

Yes, stable gravity will be unchanging with a refractometer as well. The measurement will always be incorrect once alcohol is present though.

 

[RM-MN]

So I hear that refractometers are more accurate to take OG readings and that after fermentation Hydrometers are more accurate with higher alcohol contents. I was wondering if anyone has anymore Info on this? I just took a reading of my beer that has been in the primary for 6 days and the Hydrometer reading was 1.010 and the Refractometer was 1.025... Big difference..

Hydrometers can be accurate as a refractometer for OG but the sample is so much larger and needs to be cooled prior to reading. That takes a bit of time while a refractometer can get a reading in seconds with only a drop or 2 of wort. That's why refractometers are advocated for brew day.

 

[TopherM]

I have both a refractometer and a hydrometer. I find the hydrometer to be much more accurate, but the refractometer much more convenient to use on brewday.

Of course, I have a cheap refractometer. I'm thinking of upgrading to one of the digital types, which are laboratory grade and ultra-accurate.

Like someone else said, through, you generally only use refractometers for OG readings, so you need to keep a hydrometer around if you need FG readings once alcohol is present.

 

[stpug]

So I hear that refractometers are more accurate to take OG readings and that after fermentation Hydrometers are more accurate with higher alcohol contents. I was wondering if anyone has anymore Info on this? I just took a reading of my beer that has been in the primary for 6 days and the Hydrometer reading was 1.010 and the Refractometer was 1.025... Big difference..

Refracts are great and require small sample sizes. They are quick and convenient. They are more prone to user error.

Hydros are equally great and require larger sample sizes closer to room temp. They are also regarded as a better FG check that a corrected refract reading. They are less prone to user error.

That pretty much sums it up. I personally use both, but would be more willing to roll with only a refract if I had to choose only one.

 

[stratslinger]

Refracts are great and require small sample sizes. They are quick and convenient. They are more prone to user error.

This absolutely sums it up. Refracts are great for the convenience factor - especially if you have one with automatic temperature correction. I'm able, on a brewday, to easily grab a pre-boil gravity sample or two, verify that I'm in the right neighborhood and make adjustments if necessary, then go ahead and get my OG sample just as easily - without ever having to take the time or effort to chill the sample to a temp where my hydrometer would be able to get a reliable reading. This alone is way more than worth the cost of the refract to me.

But when it comes time to get FG readings, I always go to my hydro. I've tried, particularly with 1 gallon experimental batches, to use the refract and correction tables to get readings, but I've never been particularly confident in them.

 

[pdxal]

Refractometers are great for small sample size and no need for temperature correction. If you don't mind a large amount of beer sacrificed to measure gravity hydrometers are great.
I have been comparing my refractometer readings post fermentation with correction from Sean Terrill's calculator versus hydrometer measurements for the past 20 or so batches and they have been no more than 0.02 off, and usually dead on or off 0.01.

 

[Qhrumphf]

Yet another one here who uses a refractometer for everything until I pitch the yeast. With both hydrometers and refractometers some are better than others, and some are more accurate than others. I also don't trust the ATC on mine completely, not because I think it's innacurate, but rather because those things are always limited. So if I'm taking a pre-boil gravity, I still chill it down a bit (to maybe 90-100 instead of sparge temps).

But for when you want to take a pre-boil, or even something as simple as a quick check of your first runnings gravity, or a quick check of your sparge runnings gravity to make sure you're not oversparging, you really can't beat grabbing a quick drop or two.

After yeast is pitched, it's always the hydrometer. Using a refractometer post fermentation has never been an option in my book (correction calculator or not), but I suppose next small batch that I do (1 gallonish) where I don't want to sacrifice a full hydrometer sample, I might make an exception.

 

[pdxal]

Yet another one here who uses a refractometer for everything until I pitch the yeast. With both hydrometers and refractometers some are better than others, and some are more accurate than others. I also don't trust the ATC on mine completely, not because I think it's innacurate, but rather because those things are always limited. So if I'm taking a pre-boil gravity, I still chill it down a bit (to maybe 90-100 instead of sparge temps).

But for when you want to take a pre-boil, or even something as simple as a quick check of your first runnings gravity, or a quick check of your sparge runnings gravity to make sure you're not oversparging, you really can't beat grabbing a quick drop or two.

After yeast is pitched, it's always the hydrometer. Using a refractometer post fermentation has never been an option in my book (correction calculator or not), but I suppose next small batch that I do (1 gallonish) where I don't want to sacrifice a full hydrometer sample, I might make an exception.

ATC or not, if you blow on the 1-2 drops needed to test gravity with the refractometer for 5-10 seconds they will be at or below room temp before you drop the cover and temp should be fine.

 

[Qhrumphf]

ATC or not, if you blow on the 1-2 drops needed to test gravity with the refractometer for 5-10 seconds they will be at or below room temp before you drop the cover and temp should be fine.

That's a good way of doing it. I just run the bulb of the pipette under cold tap water for a few seconds. Either way it doesn't take long.

 

[orangehero]

I think a hydrometer calibrated to wort is more accurate than a refractometer at any stage.

I know there's lots of issues with the manual refractometers, but do people have good results using a digital refractometer?

Mine does not correlate to the hydrometer reading of unfermented wort and I know it is dead nuts using calibrated sucrose solutions.

 

[mikescooling]

I can take a sample of boiling wort, by dipping my large pocket knife in, and the cooling sample can run off the tip of the knife on to the refractometer. It's fast and easy.

 

[pdxal]

I think a hydrometer calibrated to wort is more accurate than a refractometer at any stage.
Mine does not correlate to the hydrometer reading of unfermented wort and I know it is dead nuts using calibrated sucrose solutions.

I think you'll find lots of people disagree on prefermentation gravity and believe it will be dead on. Me included. After fermentation is where some disagree on the refractometer calculators' accuracy. Not sure how you are using yours, but analog/visual ones can be accurate.

 

[djfriesen]

Refractometers are great for small sample size and no need for temperature correction. If you don't mind a large amount of beer sacrificed to measure gravity hydrometers are great.


I have been comparing my refractometer readings post fermentation with correction from Sean Terrill's calculator versus hydrometer measurements for the past 20 or so batches and they have been no more than 0.02 off, and usually dead on or off 0.01.

Do you mean .002? 20 gravity points is a lot.




If it is .002, seems like a no-brainer to me. I can't really read my hydrometer any more accurately than to the nearest (2) points.

 

[Limestone_Cowboy]

I think either is fine if you just trying to determine if FG has arrived. That said, refrac for me.. between whatshisname's spreadsheet corrector and just a few drips on the glass.. win

 

[pdxal]

Do you mean .002? 20 gravity points is a lot.




If it is .002, seems like a no-brainer to me. I can't really read my hydrometer any more accurately than to the nearest (2) points.

Mis-type. .002 or less off with refractometer compared to hydrometer using Sean Terrill's conversion for alcohol calculator.

 

[chickypad]

I have been comparing my refractometer readings post fermentation with correction from Sean Terrill's calculator versus hydrometer measurements for the past 20 or so batches and they have been no more than 0.02 off, and usually dead on or off 0.01.

My experience has been the same. 19 batches out of 25 that I've compared to a hydrometer were within .001, 5 more within .002. The only one off by more than that was a saison that went down to 1.002 FG. That's good enough for me for regular use.

 

[CraigKing]

So let me get this straight - I should have both a hydrometer and refractometer?

And I should use the refracto for taking OG readings, then use my hydro for FG readings?

 

[Limestone_Cowboy]

So let me get this straight - I should have both a hydrometer and refractometer?

And I should use the refracto for taking OG readings, then use my hydro for FG readings?

no, you don't need to do that, one or the other will suffice. It's a little 'horses for courses' as far as which you prefer and how you want to approach readings. example, I brew in smaller batches.. 2.5 to 3g. It's not advantageous for me to be drawing enough beer from the fermentor to take readings everyday with a hydro for a certain stretch of days. So I thieve some drips onto a refractometer. It saves me beer. The refrac is visually accurate with any liquid so long as it doesn't have any alcohol.. like a wort. But FG readings will be skewed due to alcohol in the liquid. There's a reacharound for this; a really nice guy went through the trouble of creating an excel file for the rest of us with macros that do the math in elegant fashion. His name is sean terrill and you can google it. I love this file, because it also keep track of how my yeast have been preforming among various bathes in a single screen shot. The hydro is more or less accurate regardless of alcohol content, og or fg. Refrac is a little more expensive, but not nearly as delicate as a hydrometer over time. Partly for that reason I prefer a refrac.

 

[CraigKing]

I don't take daily readings. I only take an OG reading and a FG reading. And I brew 5gal batches.

I think I'll invest in a refractometer.