How to estimate fg

[Jesse D]

Hello all, I brewed my first brew almost 2 weeks ago, tomorrow I want to check my gravity for the first time since my og reading. It's dead ringer IPA from nb, my questions are, what should my gravity reading tomorrow, and how to estimate final gravity, thank you all!

 

[Calder]

The only way to get FG is to measure it. I would guess it should be somewhere between 1.008 an 1.012, but have not looked at the recipe. Does the recipe say what it should be?

How to estimate FG? It all depends on fermetability of the ingredients, mash temp (if you mash) and yeast, and other minor items. Can't really answer that question.

 

[Jesse D]

We

The only way to get FG is to measure it. I would guess it should be somewhere between 1.008 an 1.012, but have not looked at the recipe. Does the recipe say what it should be?

How to estimate FG? It all depends on fermetability of the ingredients, mash temp (if you mash) and yeast, and other minor items. Can't really answer that question.

Thank you, Website showed fg at 1.012 to 1.015.

 

[ba-brewer]

Calder is right in there are a lot of variables to determine FG, but for a rough first approximation ball park guess subtract the middle of your yeast attenuation range from your starting gravity points.

gravity points is stuff on the right of the decimal point multiplied by 1000

assume 75% is your middle point of attenuation and your starting gravity is 1.060
fg = 60-45 = 15 points or 1.015

 

[Jayjay1976]

More important than reaching your target FG is knowing when fermentation is complete. That means taking a reading every 2 days and when you get the same reading three times in a row, it's time to bottle.

 

[dmtaylor]

If you want to estimate final gravity, then ignore the 1.0 in front of the gravity points, and divide by 4. For example, a 1.060 OG beer should finish at approximately 60/4 = 15 or 1.015.

This is a very rough estimate and depends on the yeast strain as well. It works pretty well for American and German yeasts. But many British yeasts will not attenuate as much, while many Belgian yeasts can go way beyond and attenuate close to 1.002-1.008 or whatever.

Don't bottle too early or you could get gushers or bombs! When you think fermentation might be complete, when the yeast settles out and the airlock activity is dead, then measure specific gravity. Then wait 3 days. Then measure again. If gravity doesn't change at all in 3 days, you can bottle. Otherwise, wait 3 more days and repeat until it is stable. That's the only REAL way to know when you have reached the final-final gravity.

 

[HopHeavy]

You can get a fairly accurate measure of your anticipated FG by taking a cup or so of your wort and over pitch it with a tablespoon of your yeast starter. This will ferment out in a day or so. It will likely smell like paint thinner and offer a different taste from your final product, but you will have a very good FG target for your primary fermentation.

 

[flars]

My dead Ringer brews have finished at 1.008 to 1.009 with WY 1056 and US-05. I'll take the first SG reading about day 10 and a second about day 15 to 18 to confirm FG. The day 10 SG is usually the same as the second. The extra time in the fermentor lets the beer clear for less sediment in the bottle.

It is difficult to estimate FG. The attenuation figures given by the yeast manufacturer is only for comparisons of their yeasts. FG depends upon the fermentability of your wort.

 

[Silver_Is_Money]

Multiply the mid-range of the yeasts 'apparent attenuation' times the OG's fractional component, and subtract your answer from the OG's fractional component.

Example:

Yeasts specifications state: 67-73% apparent attenuation.
OG = 1.050

1) Midrange of apparent attenuation = 70% = 0.70
2) 50 x 0.70 = 35
3) 50 - 35 = 15

Anticipated FG = 1.015

 

[ESBrewer]

I won't measure fg three times three days apart. Because that would mean potentially introducing 3x300mg of oxygen to my 1 liter fermenter head space for total of 6 days. It is about 25 times as much oxygen that can be introduced by vigorously shaking air into the wort (a thing that many brewer's avoid doing post fermentation). Instead I just wait until yeast drops, wort clears and no visible bubbles are formed at stable temperature. Then I wait a couple of days for the yeast to clean up things and then either read gravity and bottle or transfer to secondary for dry hopping or cold crashing.

It will be fine to measure, though, if you can do it without introducing air inside the fermenter.

 

[Jesse D]

I won't measure fg three times three days apart. Because that would mean potentially introducing 3x300mg of oxygen to my 1 liter fermenter head space for total of 6 days. It is about 25 times as much oxygen that can be introduced by vigorously shaking air into the wort (a thing that many brewer's avoid doing post fermentation). Instead I just wait until yeast drops, wort clears and no visible bubbles are formed at stable temperature. Then I wait a couple of days for the yeast to clean up things and then either read gravity and bottle or transfer to secondary for dry hopping or cold crashing.

It will be fine to measure, though, if you can do it without introducing air inside the fermenter.

I'm transferring to my secondary to dry hip, it's smaller than my primary so it will have less head space, a gallon and a half less. I was going to take it while I transfer via siphon.

 

[Jesse D]

The only way to get FG is to measure it. I would guess it should be somewhere between 1.008 an 1.012, but have not looked at the recipe. Does the recipe say what it should be?

How to estimate FG? It all depends on fermetability of the ingredients, mash temp (if you mash) and yeast, and other minor items. Can't really answer that question.

Hit today at 1.012