How do you estimate the amount of sugar for a target ABV%?

Heyoh!
Just getting into this brewing thing and it's awesome. I have 2.5 gallons of pineapple wine almost ready as my first brew and just started 5 gallons raspberry lemon wine that seems to have stalled -used Red Star for it and Lalvin for the pineapple. May pitch Lalvin to re-start.

ANYWAY, my question is about sugar. I currently do NOT have a hydrometer. Have been following guidelines/ recipes. I just really want to know if there exists a chart or calc that will tell me how much total sugar to have in the wort to get out a given alcohol percentage. For example I would specify: 5 gallons and 10% ABV target, and I would receive the correct total amount of sugars that should be in the wort. Assuming I was using Lalvin EC-1118 which ferments up to 18%.

Is there some basic rule of thumb I am missing? Is it just trial and error? Because I have scoured the net and everything I have found are just suggestions and guidelines that vary a lot. I want a reliable source I can refer to. This might just be impossible without a hydrometer. But I'm sure there's a way. I want to be able to say, "Ok, this juice has X grams of sugar. In a vessel X gallons big, I need to use a total of X grams sugar to reach X ABV."

Is the percent of sugar in the water going to exactly equal the amount of alcohol it gets converted into? What's the difference by weight or volume?

Ok that's it, hope someone can help me out!
PS. On a totally unrelated matter, I know it's usually not a good idea to try and carbonate with dry ice because of inaccurate amounts and differences between headspace pressure and rate of CO2 absorption. But I think this guy has figured it out:
http://www.rickety.us/2012/07/extra-fizzy-homemade-carbonated-beverages/
All that's needed is a pressure let-off valve rated for a PSI under the rated PSI of the bottle, and some food-grade dry ice. What do you think?
ipe:

 

Well, I'd like to be able to fix my car without wrenches, and build a house without a hammer.

Get a hydrometer. I mean, is it some point of pride that you want to handicap yourself, or something?

 

You really do need a hydrometer to figure this out. Granted, the packaging on your brew ingredients will give you an estimate of what it should be. The basic idea is you will need the original gravity ready (before primary fermentation) and the final gravity reading (before bottling& priming sugars). Here some other stuff to help you.

Online calculator: http://www.angelfire.com/wi3/johnsons/abv.html
Info about hydrometer and process: http://www.brewmorebeer.com/calculate-percent-alcohol-in-beer/

Side note- get the book, "The Complete Joy of Home Brewing, 3rd Ed". EASY read and you will be glad you have it!

 

If you know the exact amount of sugar and the exact volume you can accurately calculate the starting gravity. The problem is you don't know how much of those sugars the yeast actually fermented, so the final gravity and thus the ABV will be a guess. If all goes well with a healthy fermentation you might assume you are in the estimated range, but you wouldn't know for sure without a measurement. Speaking of measurements, how do you know your batch is stalled if you don't have a hydrometer?

 

You absolutely have to have a hydrometer if you want to know. Go spend the $7 already.

Incidentally... you may get better wine answers by posting in the winemaking forum, as opposed to the beer forum. Just sayin'.

 

Well, to answer you basic question. I don't know. You can calulate ABV = 10% = .131 (o.g. - f.g) of o.g - f.g = 76 points. And you can calculate from the yeasts average attenuation how much of the sugar with be left. (If attenuation is 70 pecect then only 30 percent of the original sugar will be left.) FG = some formula of remaining sugar. So og - some formula of .3 og = 76. It'd be a matter of solving for og. But we have to know what the formula to get FG from the remaining sugar and I don't know what that is.

In the meantime, get hydrometer. You *need* one.

===
*IF* we could ignore the weight of alcohol (which we *can't*) It would be

ABV = .131 (OG - FG) = .131 (OG - (1- attenuation)OG) = .131 * attenuation * OG so
OG = ABV/.131 * attenuation.

*BUT* FG does not equal (1 - attenuation)*OG because we need to take into account the weight of alcohol that has been converted from attenuation*OG. This should be possible. Alcohol weighs .79 of water and sugar weighs... it weighs something so it can probably be figured out.

 

Plug your numbers into here until you get an appearent attenuation that agrees with your yeast.

This uses these formulas which can be manipulated to get you answer. I'd figure it out if I didn't have to run somewhere. (THese formulas don't mention the attenuation which tantamount I'd think.)

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Hmm, seems "apparent attenuation" is over 100 percent for FG < 1.000 So I think they are ignoring the effect on alcohol on FG (which lowers it to below < 1.000).

SO maybe my formula

OG = desired ABV /.131* average attenuation of yeast. Is a good guestimate.

At any rate you never going to get better if you don't buy a ****ing hydrometer.

 

---edit---

Argh! Never mind. Look at this site and figure it out:

this site

 

Hmm thanks for the answers. Guess I really need to get a hydrometer. I know they're cheap but I'm broke right now. (One of the reasons I started brewing) Priorities.. Still curious if I had a yeast with around 10% tolerance, and 10% of the wort by weight was sugar, would it all be converted? -Plus or minus the attenuation of the yeast as a margin of error. Does sugar in equal alcohol out? If not what's the conversion?

So the pineapple wine turned out so-so. I liked the taste 2 days ago then learned it is very hard to stop fermentation. I triple filtered through cloth then put it in the fridge. Yep, doing it that ghetto -used plastic water jugs too. It's pretty much stopped now, but still has to be mixed in order to drink -too damn dry. It's probably a rookie mistake to go for the highest ABV yeast and not think about drinkability. At least I didn't get turbo! Next batch will be a bit subtler- aiming for 8%-12%

 

My "Teenager Making Hooch" radar is pinging madly right now.

It has been known to throw off false positives from time to time... but...

 

^^^^ This.

 

Um.. no.

Only a portion of the sugar will be converted. That portion is the attenuation (which is not not predictable except as an average). So a yeast with 65% attenuation on average will convert 65% of the sugar on average (and *never* 100% of the sugar). The 10% tolerance means the total alcohol will never get above 10% of the total no matter how much sugar there was to begin with.

You're broke and that's why you are doing homebrew? It does *not* work that way.

 

We're not all as sophisticated as you would like. No need to be snide. Homebrew works any way I make it work, for me. I've got it from here, thanks for the info.

 

It's really not a sophistication thing... You must not be a teenager throwing bread yeast into a bottle of grape juice with some added sugar, so that means you have already invested in the equipment and ingredients you need to produce something you'll be happy with. Why draw the line at something so basic as a hydrometer? It's cheaper than a refractometer. A carboy is certainly a larger investment. Even the fruit and yeast had to cost more than a hydrometer. It is rare that getting started in brewing proves more cost effective than just buying some cheap beer/wine/whatever to catch a buzz.

Good luck.

 

What's the difference by weight or volume?

 

Alcohol weighs roughly .80 of water so there is less alcohol by weight than by volume.

ABV = 131(OG - FG)
ABW = 125(OG - FG)

but both of these are only estimates. Alcohol is determined by sugar converted and sugar converted is measurable by OG - FG so that's an accurate way of measuring total amount of alcohol but the remaining sugar (which is variable) effects the weight and volume so both are estimates.

This page gives good formulas but you have to take them on with a, metaphorical, grain of salt. (Salty beer, yuck...)