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I can't seem to keep a hydrometer for more than a few brewing sessions. They either break from dropping them, going from hot to cold, or I've had the wax holding all of the lead pellets to the bottom melt and shift the paper.

Are there any other ways to measure gravity or alcohol other than using a super delicate hydrometer?

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Why are you putting it in such hot/cold beer? Wait until it is room temperature –  Joe Philllips Jan 20 '11 at 21:01
    
I think that particular hydrometer I was cleaning under really hot water, then put it into ready to pitch wort. I think the wax one was just sitting in the sun. –  PMV Jan 20 '11 at 21:59
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5 Answers 5

up vote 16 down vote accepted

Refractometers are about the only other reasonable alternative for the homebrewer. They are a little more expensive, but usually much easier to use. They only need a few drops of wort/beer to get a good measurement. Take note however, reading final gravity of your beer is not a one step operation. You need to do a little more math if you want to calculate ABV with only a refractometer. The nice thing is BeerSmith and probably other programs will do the math for you.

The flip side to all of this is that with the larger sample needed for the hydrometer, you have a good excuse to taste your wort/beer more often. Why dump those four oz. you need for the reading when you can drink it!

Edit

Just to clear this up some. When calculating ABV of your beer, you only need two number and one simple formula. Take the OG, subtract the FG, and divide by .00736. For example, a beer that starts at 1.050 and ends at 1.010 yields (1.050 - 1.010) / 0.00736 = 5.4% ABV.

When using a refractometer, you must adjust your final FG reading. This is because alcohol and sugar are present in the sample. Alcohol refracts differently than sugar. Therefore, your FG reading on a refractometer is NOT correct on its own. You must take into account the OG when reading the FG of the beer.

This makes it a little more complex than when you just use a hydrometer. There are plenty of sites that will explain and do the calculations for you. For example, a quick Google search for 'calculating abv with a refractometer' turned up this site (Onebeer.net) which seems to do a good job.

Of course, it wants the input in %Brix, which means you don't need the refractometer with both scales...

If you really want to know what the formulas are so you can do it yourself, then go to this site (Primetab).

Edit #2

OK. I swear I'm not drinking yet. But math mistake up above. I think that should have been 0.00763. But to simplify it a bit for everyone let's just do this instead.

ABV = (OG - FG) * 131

Now, some will say "Hey! That still isn't quite right!". I agree. The relationship between SG and ABV isn't really linear. High gravity brews have some other things to factor in. Other adjuncts and flavorings can change it all up. That magic number of 131 is just a compromise. Really is can vary anywhere from about 128 to about 135. But in the sake of keeping this simple for the homebrew audience, I think that is good enough.

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+1 I love my refractometer, and I kick myself for not buying it earlier! –  pkaeding Nov 19 '10 at 17:59
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Agreed. An awesome little tool. I'd recommend using both for a while to ensure that you are getting consistent results with both (a refractometer can take some practice to use well). –  Tim Nov 19 '10 at 18:54
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Indeed. Plus, get one that is marked in %Brix and SG. That way you don't have to do any conversions. Also agree on using both for a while until you get the hang of it all. –  thebeav Nov 19 '10 at 23:56
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I know this doesn't answer your question, but how about just being more careful with the hydrometer - I've never broken one so I'm surprised that you're having so much trouble with it? In particular why would you ever use it in hot liquid (i.e. why would going from hot to cold or melting wax ever occur)?

I use a glass hydrometer but I have seen plastic ones before - I imagine they'd cope a lot better with being dropped etc.

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-1: A good rule of thumb - if you are starting your post with "this doesn't answer your question", then it is not a candidate answer and you should not post it. –  Mike S Nov 22 '10 at 0:32
    
In this case I'd say this is a valid answer. Hydrometers are fragile, but it sounds like the OP could stand to make sure he's using it correctly. Perhaps this answer could reiterate the correct procedure for using a hydrometer. –  STW Dec 11 '10 at 18:55
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the beav, not sure what you mean: "Take note however, reading final gravity of your beer is not a one step operation. You need to do a little more math if you want to calculate ABV with only a refractometer." A hydrometer doesn't do the math either.

On a different note, some measure in specific gravity. austinhomebrew.com has one for $40 this week.

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Agreed. I edited my post to clear things up a bit. I was referring to having to do more math to go from OB and FB to ABV. –  thebeav Nov 24 '10 at 16:51
    
Also note that all refractometers of the same style should cost the same. Regardless of which scales and how many they print inside the view finder. If someone is charging more for the refractometer that has %Brix and SG scales vs. the refractometer that just has a %Brix scale, then they are ripping you off. –  thebeav Nov 24 '10 at 16:52
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I too have broken so many hydrometers. My current strategy is to just be super careful with it. We treat it like a VIP now and haven't broke one in the last year or so. Use and put it away ASAP.

However, now I'm interested in refractometers. Never knew they existed.

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Refractometers can be used - they are a bit pricier, but on the other hand the sample you need is MUCH smaller. Here is a video on using one for brewing.

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