Estimate FG

[Jazzman]

I need a ROUGH guide to estimating FG. As in grams of sugar per litre will give X % alcohol and
gm malt/litre = % alcohol.
I know I need to take OG to find FG, but I'm knocking out small batches to try different hops, like 8 litres or 10 or 12 etc and need a rough guide. I put far too many ferment angles in one and ended up with over 8%, and whilst this is not a problem, I'd like to be able to guess to around half a percent when mixing up.
Can you help me please?
Thanks

 

[technobabble66]

Hey Jazzman,
Have you tried ianh's spreadsheet?
Download it here (it's the at the top of the listed topics in the Kits & Extracts sub-forum B) )
That should work to give you an FG.

BTW, if you're using sugar as a shortcut to boost up fermentables, keep in mind it lacks some of the nutrients the yeasts need, and too much by itself produces some pretty bad flavours.

 

[Yeastfridge]

www.brewersfriend.com/homebrew/recipe/calculator/

Do the maths yourself.

 

[TheWiggman]

Asking for a rough guide to a complex problem will mean rough answers. There are various calculators on the internet that will help you out on a need-be basis.

For OG you're looking at the density of the sugar in solution to calculate it. A rough guide is -

Table sugar
1 kg of sugar in 10l will give an SG of around 1.038.

LDM
1 kg in 10l gives around 1.040

Adjust your sugar level to adjust SG - half the sugar will result in half the 'points' i.e. 500g = SG of 1.019

For FG, again very varied but you can use apparent attentuation (say 75% for malt) of the yeast on your points to determine FG. A raw sugar solution will attentuate much more than that, up to 100% from what I've read.

46 * (1-0.75) = 1.011 FG

However, sugar is much more fermentable than malt and will attentuate more.

For basic ABV calculation, ABV = (OG - FG) * 131.25

So, by extension -

• 1kg sugar in 10l = 5.0%
• 1kg LDM in 10l = 3.8%

All the above will only be right in one specific applicaton and will vary depending on many things, but even a stopped clock is right twice a day. Just don't expect consistent results.

 

[Jazzman]

Thanks very much Wiggman. That's all I need. A really thorough reply and most appreciated. I know it'll be approx but will help me not make the rocket fuel I've been making!
And thanks everyone else. I'll check those calculators tonight.
I knew about Ian's spreadsheet but only got Japanese type script when I tried to open it last night.
Thanks again.

 

[Jazzman]

Hey Yeastfridge!
That calculator is a ripper!
Thanks.