Pre boil reading

[dustinthompson85]

So when doing an all grain batch and you're taking a pre boil gravity reading how many points can you be off before you start to see a drastic change from what you're going for? I'm making a beer that's supposed to be 9% alcohol but I could go a little bit lower without being upset but not sure how many points I could lose on my pre boil reading before it becomes too big of a problem. I haven't looked at my efficiency ratings before and I'll have some dry extract in case I'm too low just don't know when I should use it. Any advice outside of making the reading perfect?

Sorry if I am not getting my question out clearly.

If my pre boil target is 1.089, how close do I really need to be?

 

[Tribe Fan]

Depends on batch size and evaporation rates, but here's a calculator you can play with.
https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

 

[dustinthompson85]

Depends on batch size and evaporation rates, but here's a calculator you can play with.
https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

End result will be 5 gallons. How would I know what my new estimate post boil reading would be if I am a few points short of the pre boil? Maybe I am over complicating it and just need to wing it.

 

[Tribe Fan]

End result will be 5 gallons. How would I know what my new estimate post boil reading would be if I am a few points short of the pre boil? Maybe I am over complicating it and just need to wing it.

On something that big minus 10 points would not worry, nor surprise me. Efficiency will tend to be lower with big grain bills. If it's really low, like half, then there is a mash problem.

You can always boil longer, just don't add your hops until you know you have 60 minutes left, that is what the calculator will help with.

You can add dme, but remember that about 25% of that gravity will not ferment, but will provide malty flavor and mouthfeel.

If you want pure gravity to ferment to alcohol use sugar.

I almost always just go with what I've got, but I'm just looking to drink good beer, not entering competitions and the like. For reference here's where I came in at on some recent batches of pale ale's:
Expected 1.046 - actual 1.046
Expected 1.047 - actual 1.053
Expected 1.044 - actual 1.040

For me, this is largely a factor of efficiency. If I was brewing a bigger beer, they would be off by a factor of 2x.

 

[AZCoolerBrewer]

I haven’t started running numbers in the calculators but my gut tells me that a pre-boil of 1.089 will give you a beer that is higher than 9%.

So just tossed the numbers into brewers friend and for 9%, I would go for mor like 1.074 pre-boil.

 

[Reavers2013]

End result will be 5 gallons. How would I know what my new estimate post boil reading would be if I am a few points short of the pre boil? Maybe I am over complicating it and just need to wing it.

Take your preboil volume multiply by preboil gravity points (i.e. 1.089 gravity is 89 gravity points) then divide by your final volume. That will give you your final gravity points. (Preboil points times preboil volume equals post boil points times postboil volume)

 

[hottpeper13]

Make sure when taking volume measurements that you take into account thermal expansion of 4% above 190*. What I do is take the measurement number and multiply by .96 and the result is the actual cooled volume.