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Gravity Readings And %

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hamstringsally

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ok so bear with me here but the way ive been working out my alcohol percentage is taking my reading of pre boil and OG with a calibrated refractometer.

usually the reading on the same recipe is around 1.045 to 1.046 for my OG'S.

all my final readings are at 1.010

with the chart ive got with my hydrometer is stating that the estimated % of alcohol is at around 4.5 to 4.6 % if

1.045 = 5. 8% (OG)
1.010 = 1.3% (FG)

5.8 - 1.3 = 4.5 %

is this pretty accurate or is there a better accurate way to work this out?

cheers

hammo
 

warra48

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ok so bear with me here but the way ive been working out my alcohol percentage is taking my reading of pre boil and OG with a calibrated refractometer.

usually the reading on the same recipe is around 1.045 to 1.046 for my OG'S.

all my final readings are at 1.010

with the chart ive got with my hydrometer is stating that the estimated % of alcohol is at around 4.5 to 4.6 % if

1.045 = 5. 8% (OG)
1.010 = 1.3% (FG)

5.8 - 1.3 = 4.5 %

is this pretty accurate or is there a better accurate way to work this out?

cheers

hammo
Matches what BeerSmith gives me.
http://beersmith.com/

Plus you need to add about 0.5% or so for your priming medium.
 

wbosher

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ok so bear with me here but the way ive been working out my alcohol percentage is taking my reading of pre boil and OG with a calibrated refractometer.

usually the reading on the same recipe is around 1.045 to 1.046 for my OG'S.

all my final readings are at 1.010

with the chart ive got with my hydrometer is stating that the estimated % of alcohol is at around 4.5 to 4.6 % if

1.045 = 5. 8% (OG)
1.010 = 1.3% (FG)

5.8 - 1.3 = 4.5 %

is this pretty accurate or is there a better accurate way to work this out?

cheers

hammo
Apparently subtract the FG from the OG and multiply by 131.

1.045-1.010=0.035*131 comes to 4.59

Saw that on the net somewhere so don't know how accurate it is, but looks pretty close.
 

bignath

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ok so bear with me here but the way ive been working out my alcohol percentage is taking my reading of pre boil and OG with a calibrated refractometer.

usually the reading on the same recipe is around 1.045 to 1.046 for my OG'S.

all my final readings are at 1.010

with the chart ive got with my hydrometer is stating that the estimated % of alcohol is at around 4.5 to 4.6 % if

1.045 = 5. 8% (OG)
1.010 = 1.3% (FG)

5.8 - 1.3 = 4.5 %

is this pretty accurate or is there a better accurate way to work this out?

cheers

hammo
Two things....

Firstly,what difference does preboil gravity make, and where does it function in your formula? I don't get it...

Secondly, where does the 5.8 and 1.3 come from, how's that worked out? I don't get that either...

Whilst my gut tells me that an OG and FG of those numbers will be close to 4.5%ABV, i don't follow what your proposing.

ABV% is directly related to both the OG and FG of a particular batch. Ie: if your beer always finishes at the same FG, but your OG was higher, then so will be your abv. If your OG was the same, but had a batch finish lower, the abv will also be higher.
 

hamstringsally

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Apparently subtract the FG from the OG and multiply by 131.

1.045-1.010=0.035*131 comes to 4.59

Saw that on the net somewhere so don't know how accurate it is, but looks pretty close.


interesting! that was something i was looking for. Can you remember where you saw it? Im looking for a nice secondary formula to run by the original to get a bit more accurate with %.

Other reason i wonder is because i picked up the latest version of Beer and brewer mag (spring edition) today and was reading through home brewer recipes. one was the old red settler IRISH RED ALE full mash recipe. The expected brew figures say OG 1.042 and FG 1.010 with a alcohol content of 4.5% and made me question my methods??
 

hamstringsally

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Two things....

Firstly,what difference does preboil gravity make, and where does it function in your formula? I don't get it...

sorry mate my bad really didnt need to mention pre boil

Secondly, where does the 5.8 and 1.3 come from, how's that worked out? I don't get that either...

of hydrometer chart

Whilst my gut tells me that an OG and FG of those numbers will be close to 4.5%ABV, i don't follow what your proposing.

ABV% is directly related to both the OG and FG of a particular batch. Ie: if your beer always finishes at the same FG, but your OG was higher, then so will be your abv. If your OG was the same, but had a batch finish lower, the abv will also be higher.


how do you work out your % mate?
 

Juzdu

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interesting! that was something i was looking for. Can you remember where you saw it? Im looking for a nice secondary formula to run by the original to get a bit more accurate with %.

Other reason i wonder is because i picked up the latest version of Beer and brewer mag (spring edition) today and was reading through home brewer recipes. one was the old red settler IRISH RED ALE full mash recipe. The expected brew figures say OG 1.042 and FG 1.010 with a alcohol content of 4.5% and made me question my methods??
In the little round "Brewing Record" papers that come with the Coopers kit cans, they have the ABV formula on page 3. It says OG - FG, divided by 7.46 gives you the ABV. Then they say to add 0.5% if priming.

That's the same formula as OG-FG multiplied by 0.134 btw.
 

bignath

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how do you work out your % mate?
Either one of two ways....

1. Last two numbers of OG-FG / 7.46

No idea where the 7.46 comes from. I saw it on the net when i first started brewing nearly 10years ago. Seems to be pretty accurate.
OG 1.045
FG 1.1010

45-10 / 7.46 = 4.69

OR;

2. Rely on my brewing software.

As i brew all grain, i've got my recipe in front of me on my dedicated "comBREWter" and i fill out all my gravity readings at all appropriate places in the software and it tells me where it's all at so i don't need to use the formula anymore.
 

QldKev

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Throw another kilo of sugar in, then you'll be too pissed to care :D
 

yum beer

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Throw another kilo of sugar in, then you'll be too pissed to care :D

HA,

6 point who gives a shit %

I also use the (OG - FG) x .134 plus .5% for priming.(which is something to remember when using software because you need to allow for it.)
 

wbosher

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HA,

6 point who gives a shit %

I also use the (OG - FG) x .134 plus .5% for priming.(which is something to remember when using software because you need to allow for it.)

Just Google "calculate alc vol" or something similar. Heaps of calculators out there.
 

431neb

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HA,

6 point who gives a shit %

I also use the (OG - FG) x .134 plus .5% for priming.(which is something to remember when using software because you need to allow for it.)
That method requires you to drop the decimal point out doesn't it? I have always used the same but multiplied by .14 . It seems looking at everyone elses numbers that I might be better off using .134. It's easy to remember anyway (see my nic).

My method 1.045 x 1.010 = .035 Therefore ...drop decimal 35 x .14 = 4.9 (Plus .5 for priming of bottles if needed).

I will research further now as I may have been getting it wrong.
 

yum beer

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That method requires you to drop the decimal point out doesn't it? I have always used the same but multiplied by .14 . It seems looking at everyone elses numbers that I might be better off using .134. It's easy to remember anyway (see my nic).

My method 1.045 x 1.010 = .035 Therefore ...drop decimal 35 x .14 = 4.9 (Plus .5 for priming of bottles if needed).

I will research further now as I may have been getting it wrong.

Yes drop the decimal, just use your last 2 numbers...45-10 = 35 X .134 = 4.69%
 

np1962

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Two things....

Firstly,what difference does preboil gravity make, and where does it function in your formula? I don't get it...

Secondly, where does the 5.8 and 1.3 come from, how's that worked out? I don't get that either...

Whilst my gut tells me that an OG and FG of those numbers will be close to 4.5%ABV, i don't follow what your proposing.

ABV% is directly related to both the OG and FG of a particular batch. Ie: if your beer always finishes at the same FG, but your OG was higher, then so will be your abv. If your OG was the same, but had a batch finish lower, the abv will also be higher.
Firstly- We should assume the OP made a typo and meant to say Post Boil as he goes on to talk about his OG
Secondly - The figures are the potential alcohol from the sugars available if fermented to 1.000SG. i.e. a 1.045og wort has the potential to produce 5.8% abv if femented out fully.
Can be a reasonably accurate way of estimating abv.
Nige
 

np1962

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Two things....

Firstly,what difference does preboil gravity make, and where does it function in your formula? I don't get it...

Secondly, where does the 5.8 and 1.3 come from, how's that worked out? I don't get that either...

Whilst my gut tells me that an OG and FG of those numbers will be close to 4.5%ABV, i don't follow what your proposing.

ABV% is directly related to both the OG and FG of a particular batch. Ie: if your beer always finishes at the same FG, but your OG was higher, then so will be your abv. If your OG was the same, but had a batch finish lower, the abv will also be higher.
Firstly- We should assume the OP made a typo and meant to say Post Boil as he goes on to talk about his OG
Secondly - The figures are the potential alcohol from the sugars available if fermented to 1.000SG. i.e. a 1.045og wort has the potential to produce 5.8% abv if femented out fully.
Can be a reasonably accurate way of estimating abv.
Nige
 

bignath

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...Secondly - The figures are the potential alcohol from the sugars available if fermented to 1.000SG. i.e. a 1.045og wort has the potential to produce 5.8% abv if femented out fully....
Ahh, got it.

Have never heard of that before, cheers Nige.
 

ianh

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interesting! that was something i was looking for. Can you remember where you saw it? Im looking for a nice secondary formula to run by the original to get a bit more accurate with %.
I use the 131 factor in my spreadsheets. It came from a UK goverment website for determining %alcohol and hence duty on beer. The factor changes depending on the OG.

Unfortunately a quick Google search could not find the site.
 

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