My abv calculation always seems to high

[accordpower99]

When i use the formula og-fg x 131 i got 14 percent for my double ipa batch and for my ipa batch 11percent.
I thought well im doing something wrong but when you punch in the numbers from the instructions that come with the kits it has the same results.

What am i missing?

Also is there a measurement tool that measures the alchol contant without abv calculator?

 

[frazier]

Well, I can't tell what you're missing, if you don't "show your work".

What was your OG? What was your FG? How did you measure them?

Yes there is a piece of lab equipment that can directly measure alcohol content, I believe. It is expensive, and more complicated to use than doing a simple piece of math.

 

[JollyIsTheRoger]

What were the og and fg readings? Maybe the math was wrong, or if you topped up with water you just took a thick sample that wasn't mixed well

 

[aiptasia]

An alternate formula: ABV = (((1.05 * (Starting SG – Final SG)) / Final SG) / 0.79) * 100

ex: (((1.05 * (1.050 - 1.010)) / 1.010) / .0.79) * 100
(((1.05 * 0.040 / 1.010)) /.79) * 100
(0.0416 / .79) * 100
5.27% abv

Just remember your orders of operation (PEMDAS): Parenthesis, Exponents, Multiply, Divide, Add and Subtract.

 

[frazier]

Just remember your orders of operation (PEMDAS): Parenthesis, Exponents, Multiply, Divide, Add and Subtract.

Or, just remember to RDWHAHB.

 

[accordpower99]

Well I had taken two samples for og because i am not sure when i taken the reading. I take one after i transfer wort to the fermenter @ 3 gallons. Then another sample after i fill up to 5 gallons with water. I usually take the last bit of remaining beer after i make the transfer to test with my hydrometer.
SO OG @ 3 gallon wort- 1.12
@5 gallon- 1.055
FG- 1.016
Im thinking something is up with my OG reading. but regardless of which number i use it comes nowhere near the 7-8% of where its suppose to be at

 

[Cathedral]

Did you account for temperature? Most hyrdometers are calibrated for 60*F and if you didn't adjust the reading for termp it will be off.

 

[Cathedral]

Well I had taken two samples for og because i am not sure when i taken the reading. I take one after i transfer wort to the fermenter @ 3 gallons. Then another sample after i fill up to 5 gallons with water. I usually take the last bit of remaining beer after i make the transfer to test with my hydrometer.
SO OG @ 3 gallon wort- 1.12
@5 gallon- 1.055
FG- 1.016
Im thinking something is up with my OG reading. but regardless of which number i use it comes nowhere near the 7-8% of where its suppose to be at

You take the OG after you top up, right before you put it away to ferment. Using your numbers I get 5.11% ABV

 

[Golddiggie]

Use this site... with your actual OG (at full volume) and FG numbers. IF the sample temperature is not at 60F, take a temperature reading and enter those values too.

BTW for 1.055 OG and 1.016 FG, at 60F, you get 5.2% ABV.

Also, with topping off, unless you mix REALLY WELL, the sample can be very different than the actual. If you're brewing extract, then assume that the recipe (or software) is giving you the correct OG (assuming your volumes are correct). Lots of assuming on your part.

 

[chickypad]

As was mentioned, it's really hard to get a good value topping off - but luckily you can calculate because you took one before. If you trust your volumes, at 3gal you had 120 gravity pts: 120*3/5 = 72. So I'd use OG 1.072 and FG 1.016 to get 7.35%. That puts you in range for what you were expecting sounds like. The mixed OG after topping off must have been wrong.

 

[accordpower99]

No i didnt test at 60 degrees. Alot of good info here thanks. It taste like a 7 plus percent for sure it taste awesome for a double ipa is the only accurate measurement i have had so far lol

 

[Yooper]

Well I had taken two samples for og because i am not sure when i taken the reading. I take one after i transfer wort to the fermenter @ 3 gallons. Then another sample after i fill up to 5 gallons with water. I usually take the last bit of remaining beer after i make the transfer to test with my hydrometer.
SO OG @ 3 gallon wort- 1.12
@5 gallon- 1.055
FG- 1.016
Im thinking something is up with my OG reading. but regardless of which number i use it comes nowhere near the 7-8% of where its suppose to be at

Well, as was mentioned, you add the water to top up to 5 gallons, and then take the reading as close to 60 degrees as possible. There is a correction for temperature if the sample is warmer.

but in this case, (1.055- 1.016) x 131 = 5.1% ABV.

There is no point in taking an OG sample of the 3 gallons, as that is not of any use at all. The OG (original gravity) is the measurement of the total volume of the wort.

 

[beergolf]

Well I had taken two samples for og because i am not sure when i taken the reading. I take one after i transfer wort to the fermenter @ 3 gallons. Then another sample after i fill up to 5 gallons with water. I usually take the last bit of remaining beer after i make the transfer to test with my hydrometer.
SO OG @ 3 gallon wort- 1.12
@5 gallon- 1.055
FG- 1.016
Im thinking something is up with my OG reading. but regardless of which number i use it comes nowhere near the 7-8% of where its suppose to be at

Was it an extract brew? What was the recipe? If so what did the recipe call for as OG? My guess is that after you topped off the wort and the water was not fully mixed and you reading was off.

With an extract brew it is near impossible to miss OG unless your volumes are way off

 

[chickypad]

There is no point in taking an OG sample of the 3 gallons, as that is not of any use at all. The OG (original gravity) is the measurement of the total volume of the wort.

But you can calculate the 5 gallon OG from the gravity of the 3 gallons of wort, if the volumes are accurate. If someone was worried about the mixing issue it seems like this would actually be a more accurate way to measure.

Or as mentioned OP, if this is extract batch you could just assume your gravity is what the recipe calls for if you added all the ingredients and your volume is accurate.

 

[ajf]

I agree with chickypad. The measurement of the 3g gravity does not agree with the measurement of the 5g gravity, and the most likely explanation is inadequate mixing after adding the top off water. However, applying temperature compensation to the gravity readings will improve the accuracy of the calculations.

-a.

 

[pabloj13]

i agree with chickypad. The measurement of the 3g gravity does not agree with the measurement of the 5g gravity, and the most likely explanation is inadequate mixing after adding the top off water. However, applying temperature compensation to the gravity readings will improve the accuracy of the calculations.

-a.

+2

 

[accordpower99]

Yes it is was a extract brew kit its was a hop head ipa kit recipe and i believe my og is off from what the kit calls for mt fg was on point though ive had this issue for awhile.

 

[logan3825]

If you used all the extract and sugars that came with the recipe I wouldn't even bother taking an OG. I rarely take an OG anymore when I do extract. Just a FG. As long as you are at the right volume in the fermenter your OG should be good.