Specific gravity

[wiggins]

How do you go about roughly working out the og and fg of a brew just from ingredients?

[Hashie]

Brew-craft have a simple brewers calculator, it can be found here http://www.brewcraft.com.au/wawcs019616 ... lator.html

It will give you OG and FG just from ingredients.

[HopsAlot]

I just ran my last (and only) 3 brews thru this calculator, the calculator is way different from my actual results. The calculator shows much higher alcohol content. Also I am assuming when it says total volume on their web calculator they mean liters not KG! It could be I am using the calculator incorrectly.

The OG's look ok but the FG look way to low compared to my actual results. (I am using palmers table for my abv calcs).
Me: Batch 1: OG 150 FG 118 abv = 4.1%
Calculator: OG 157 FG 115 abv = 6.2

Me: Batch 2: OG 160 FG 120 abv = 5.1
Calculator: OG 158 FG 116 = 6.1

Me: Batch 3: OG 146 FG 120 abv = 3.2
Calculator: OG 151 FG 115 abv = 5.4

Anyway appreciate the exchange! Thanks in advance!

[vitalogy]

Same here, it gives me much higher results. I usually use the formula
Alc% = (OG - FG) / 7.46 + 0.2

[HopsAlot]

Thanks vita, could be a bug in their program, or maybe the measurements I am making on my batches are not all that accurate....

[MHD]

This is another, slightly more complex site
http://hbd.org/cgi-bin/recipator/recipator

Your kit is just extract for the purposes of OG

[da_damage_done]

Here is a direct link to the actual calculator (shockwave file) should anyone wanna save a local copy to their computers

http://www.brewcraft.com.au/webfiles/Br ... mator1.swf

Cheers

.swf files open in most browsers e.g. Firefox or Internet Explorer

[Cheeno]

The whole question of determining ABV seems to me a curly one. I was turning out some nice enough brews but they were tending more towards the 4.0-4.4%ABV range while everyone (kit producer, brewcraft calc. HBS etc) was assuring me of 5.0%. No problem thinks I, I'll just add 250g extra fermentables. For the first attempt instead of the usual 1kg BE I used Ikg LDME and 250g of Dex. giving me 5.4% according to the calc. @22L The OG was 1068 (which I am extrerely dubious about) and the FG 1014 = 8.1% Put that one down to not stirring enough I guess. Next I used 1kg BE and app.150g honey and stirred it good. Without the honey I should have been looking at 1040 but that 150g meant OG 1050 FG 1010 ABV=6.1%. This happened a few more times. For my last endeavour I went back to the kit and kilo(BE) method. I followed the same procedure as I always have except the extra fermentables. The temp. at reading was the same as for the other brews and lo and behold I'm back to 1042. Maybe it's the way I add the extras

[Dogger Dan]

Do you really want to do it from scratch? Been a while but I can still post it.

Truthfully, the best way is to buy either Beer Smith or Pro Mash

I like Beer Smith


Dogger

[Hashie]

Sure is some discrepensie re-alcohol.

I use this chart http://www.countrybrewer.com.au/images/ ... 0Chart.pdf from the country brewer, to get an idea of where my beer is at.

It could be right, it could be way off. All I know is after a few litres of brew, my legs get wobbly.

[Rubber.Piggy]

I've never tracked alcohol content precisely, I do measure it, and I tend to be 1-2% lower than the "suggested" result, but I don't care. For me it's all about taste, not alcohol. Besides if my brews have less alcohol I can drink more of them

EDIT: Are you guys using your hydrometers at the calibrated temperature?? There will be a bigger difference in result than you think.

[vitalogy]

EDIT: Are you guys using your hydrometers at the calibrated temperature?? There will be a bigger difference in result than you think.

I've never really looked into this. I'm assuming most stock-standard hydrometers are calibrated for room temperature (around 20deg)? And if the sample has a higher temp then it will give a higher reading?

Sorry it's been a while since year 12 chemistry

[undercover1]

The easiest way to track it is by proper hydrometer readings at the start & finish of your brew. Is there a reason you can't do it this way, wiggins?

Even those can be thrown out by temp variations, but the margin is not as great as using "typical" ingredient compositions/contributions for your calcs but using actual ingredients for your brew.

[MHD]

EDIT: Are you guys using your hydrometers at the calibrated temperature?? There will be a bigger difference in result than you think.

I've never really looked into this. I'm assuming most stock-standard hydrometers are calibrated for room temperature (around 20deg)? And if the sample has a higher temp then it will give a higher reading?

Sorry it's been a while since year 12 chemistry

Most hydros are calibrated for 20 degrees
The higher the temperature the thiner the liquid (think about a cold car engine and the oil)
for example (and from memory) a hydro reading of hot wort at 67 degrees of 1080 is about 1095 corrected back to 20 degrees

mmm first runnings

[MHD]

and yes... get a hydrometer, it is the only way to be sure...
ingredients, such as malt extracts, will have slightly different OG and some times quite different FGs depending on the manufacturing proccess

for example, with malt extracts, if the manufacturer mashed at a higher temperature he will get more unfermentable sugars meaning a higher FG...

[Cheeno]

I agree 100% re the taste factor RP. I just find the whole thing slightly amusing (bemusing) and was having a bit of a play. I'm quite happy with 4% if the beer is nice. If I want more alcohol I'll make wine.
Oliver kindly posted a temp correction guide for Hydros calibrated to 20C but it did not explain the 10points I achieved with just 150g honey?

[vitalogy]

Most hydros are calibrated for 20 degrees
The higher the temperature the thiner the liquid (think about a cold car engine and the oil)
for example (and from memory) a hydro reading of hot wort at 67 degrees of 1080 is about 1095 corrected back to 20 degrees

Okay, cheers for that. So it sounds like when you take a reading a couple of degrees above or below 20 degrees, then the margin of error would be negligible?

[chris.]

Most hydros are calibrated for 20 degrees
The higher the temperature the thiner the liquid (think about a cold car engine and the oil)
for example (and from memory) a hydro reading of hot wort at 67 degrees of 1080 is about 1095 corrected back to 20 degrees

Okay, cheers for that. So it sounds like when you take a reading a couple of degrees above or below 20 degrees, then the margin of error would be negligible?

It's bugger all difference over a few degrees.
Most beer recipe programs (promash, beersmith etc) will have a calculation tool to reference.

It's also a good idea to check that your hydrometer is calibrated properly by placing it in 20degree water & making sure it reads 1.000.
I recently found one of my hyrometer's that i'd been using for over 6 months was almost 10 points out.

[MHD]

About a point over 3 or 4 degrees... from memory...

so no biggie...

[Rubber.Piggy]

I agree 100% re the taste factor RP. I just find the whole thing slightly amusing (bemusing) and was having a bit of a play. I'm quite happy with 4% if the beer is nice. If I want more alcohol I'll make wine.
Oliver kindly posted a temp correction guide for Hydros calibrated to 20C but it did not explain the 10points I achieved with just 150g honey?

Playing never hurt anyone

I'm not sure, but I suspect that different qualities of honey will give you different SG readings because of the variation composition (check the label??). Perhaps Dogger knows if this is true.