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Since I've started brewing, I've been less than satisfied with my OG readings. They tend to be too high for the style.

At first I thought it could be the addition of the yeast before sampling, so I stopped that habit.
Then I thought it could be that I allow too much sediment in the beer from adjuncts, so I let it settle out before reading.
Neither of these have helped.

I already adjust the gravity for temperature but, for example, a Tripel I brewed came in at 1.100 OG @ 68 degrees with 9lbs of LME and 1.5 lb of pre-boil adjunct for a 5 gal batch. This gravity was the same before settling and after and the sample was taken before adding yeast.

I'd like to continue taking gravity readings rather than rely on a gravity calculation based on sugars so any help would be great.

Dave, are you yielding 5 gallons after boiling?

Most recipies are set up to finish with 5.5 gallons and yield 5 to the fermenter. This means that you need to start with at least 6.5 gallons of water to allow for boil-off.

It sounds like your boiling down and concentrating the sugars. You can just dilute back to your target OG.

Hey Dave...me again (sorry...kinda bored). I haven't done extract in many years, nor tried to calculate extracts without my software in even longer, but here's what I think. LME provides about 37 points (.0037) of extract per pound, per gallon. If you're using 9 pounds in a 5 gallon batch, that should be an extract total of 1.166 (.0037 X 9) / 5 = .1665. And if you're ending up with 5 full gallons (or 5.5 in the kettle, post boil), your gravity should actually be higher than 1.100. (That's if my math is right...I'll check when I'm not at work).

Be sure you're calculating your expected extract BEFORE you start brewing, be sure you start with 6.5 - 7 gallons of wort pre-boil (to end up with about 5.5 in the kettle). Also, the temp will affect gravity, so you need to compensate for that using the sheet that came with the hydrometer...as it sounds like you did). Proteins, etc. in the cooled wort will not affect the readings, settled or otherwise. And unless you're Bill Lawrence, DO take before and after gravity readings. Only Bill can make good beer without really trying!

Hey guys, I boil 3 gal (down to about 2-2.5) of wort and add 2.5-3 gal of liquor to my carboy to bring it up to the 5 gallon batch.

Do you actually rack off the wort to the fermenter (to get 5 gal from 5.5), brewboy? I pour it, sludge and all (hopsacks and grain bags used and removed) in.

Yes, you should try to rack the wort off the crud in the kettle. You really don't want the debris in the fermenter, though there are some who argue it provides needed nutrients. I've always tried to move the cleanest possible wort into the fermenter via the use of a false bottom, SS cloth filter, and a little wall like thingy that blocks hops from leaving through the valve. In fact, if you're doing a lager, it's a rather common practice to move the wort to an intermediate container, let the wort cool to 40ish for awhile so all the proteins, etc. will settle out, then rack it to your fermenter.

Now let me check my calculations...

OK, I'm glad I qualified my calculations above by stating that I was a bit out of practice. Turns out that the OG for 9 pounds of LME in a 5 gallon batch should have resulted in an OG of something closer to 1.067. (9lbs X 37 gravity poits / 5 gallons). You didn't mention what the other 1.5 pounds of adjunct were but, let's assume it was cane sugar. At 46 points per pound/gallon, this would add another .014 points, bringing your total expected OG to about 1.081.

So, unless I'm making some gross mistakes here (which is very likely...), I don't see how you got to 1.100 if you really wound up with 5 gallons.

I'm going to continue refreshing my memory on manually calculating extracts but, in the meantime, I'm hoping one of our better educated peers will chime in and either verify my rough calculations or explain how it's really done.

By the way, I appreciate your questions. They make me/us think and work things out...things we may have long since forgotten. It's really valuable, at least for me, to go back over this stuff. So keep it coming!

I was never happy with the gravity readings taken with a hydrometer with hot wort. First of all, you should have an idea of what your gravity should be pre-boil. You can use this to determine your estimated post boil gravity.

Let's work at this backwards. I will use some even numbers to make it easier. Let's say you want to end up with 5 gals of 1.050 beer. So, let's forget the 1.0 and just use the 50.
5 gals x 50 = 250 gravity points.

Now, let's say you are going to boil 3 gallons down to 2 gallons. No matter how many gallons you have you will still have the same number of gravity points.
250 / 3 = 83.3 or a gravity of 1.083 or 1.084 preboil.

If you boil down to 2 gals you would still have 250 gravity points.
250 / 2 = 125 or 1.125 for a post boil.

Now, rather than using the hydrometer for this I suggest you spend a little and purchase a refractometer. If you don't want to spend a lot of cash check Craig's list, the for sale forum. I bought one that works great from William's Brewing for a little more than $50. You can take your gravity reading very quickly and make the necessary adjustments with confidence. I always have to take 2 or three readings to make sure it is correct but it is still quicker and more acccurate than adjusting the hydrometer reading for temp. At least it is for me. Maybe your results are different.

Hey Chris. I think your new math is right. I used 1.5 lbs of malted barley pre-boil (forgot which) and 2 lbs of beet sugar added to the secondary. My gravity reading was going into the primary though. I think my trub is the culprit, settled or not. I would expect close to 1.0700 in the primary with an additional .0184 from the sugar in the secondary for a total of 1.0884 which matches the style.

kingsbrew, I have been relying on the recipies and just taking gravity reading after adding the liquor rather than testing the boiled or pre-boiled wort. I like this idea though for when I get more rigorous, but how do you get the preboil gravity to the level you want? I assume you mash and the sweet wort is already been made in full. Never heard of a refractometer, but I'll look into it.

kingsbrew wrote: .

Let's work at this backwards. I will use some even numbers to make it easier. Let's say you want to end up with 5 gals of 1.050 beer. So, let's forget the 1.0 and just use the 50.
5 gals x 50 = 250 gravity points.

Now, let's say you are going to boil 3 gallons down to 2 gallons. No matter how many gallons you have you will still have the same number of gravity points.
250 / 3 = 83.3 or a gravity of 1.083 or 1.084 preboil.

If you boil down to 2 gals you would still have 250 gravity points.
250 / 2 = 125 or 1.125 for a post boil.

So let me hijack this a little bit to try to take the fine math above and equate it to a recipe found or would like to build..

I go to the BJCP Style Guidelines , say pick a style, 10A. American Pale Ale , and it tells me

Vital Statistics: OG: 1.045 – 1.060
FG: 1.010 – 1.015

now let's say I shoot for OG 1.050 and I want 5 gals and based upon what you stated above I want 250 gravity points

now earlier it was stated that LME was approximately 37 gravity points per lb so for my basic recipe I want 6 3/4 lbs of LME?

Now if I was doing non-full boils say I ended up with a 2 gal wort, approx. 1.125 if i add the requisite liquor (water?) to my fermenter to reach a full 5 gals, should the OG: read 1.050 ? approx.

RobDrechsler wrote:now let's say I shoot for OG 1.050 and I want 5 gals and based upon what you stated above I want 250 gravity points

now earlier it was stated that LME was approximately 37 gravity points per lb so for my basic recipe I want 6 3/4 lbs of LME?

Now if I was doing non-full boils say I ended up with a 2 gal wort, approx. 1.125 if i add the requisite liquor (water?) to my fermenter to reach a full 5 gals, should the OG: read 1.050 ? approx.

If you assume your water is 1.000 (and you can measure it), and you want 1.050, then you would need 250 points for a 5 gallon batch, yes, or 6.75675675675... lbs of LME at 37 points/lb.

When I was only doing partial boils (3 gallons or so), I would measure the gravity of the wort before my water addition (because it was easier since I did the top-off directly to the carboy) and then add 1.0 for each gallon of water I added, and average it out. It is not as accurate as it could be, but it starts to get you there.

So if I had 3 gallons of wort that measured 1.100 and I added 2 gallons of water at 1.0, then I would have ((1.10*3) + (1.00*2))/5 = 1.060 OG

Does that help?

All that math is correct. But you might want to verify that 37 oints per pound I threw out there. That was based on a really old book I was reviewing. But you have the formula ((pounds X points)/gallons) so you should be good to go.

Regarding the OG, it sure would be easier to just validate it either with the full 5 gallons (using a wine thief or similar tool) or a refractometer, as Leroy mentioned. What's another $75 bucks when there's good beer at stake?!

Maybe this has already been suggested, but have you checked to see if your hydrometer is properly calibrated? Plain water should measure right around 1.000. I'm wondering if your's would measure it higher. I read once in AHA TechTalk, that a brewer's hydrometer was off by about 20 points because the paper inside had slipped. Maybe the same has happened with yours?

Einar

Eric raises an excellent point, and that was the first thing that crossed my mind when I read the original post. Bring your hydrometer to a brew day and you can test it side-by-side with others and also compare it to people's refractometer readings. There is undoubtedly also some variation in gravity points per pound between the various brands and types of LME. However, I would not expect those variations to be enough to account for the large OG error you are reporting. How are your beers finishing out? Are you getting pretty close to the predicted FG?

The hydrometer reads 1.000 in tap water (or very close to) and my final gravities are usually pretty close to what i would expect with calculated original gravities. For example, thet Tripel dried out to 1.014 which seems a little low, but I did let the yeast eat all that good barley sugar before adding the sucrose to the secondary (and it was there for a month). HBHQ said that would set a lower FG. And 1.014 seems to match with the attenuation based on the original 1.06 calculated.

But that's a great idea to bring it along and test it against one of those refractometers.