Starting off with all 6 gallons

[Abide]

I apologize if this has been covered I could not find the answer. I have a 6 gallon brew (stout) I burn about 1 1/4 off in the boil. does it hurt me to start off with all 6 gallons? When I'm done I'm left with just over 4 1/2 gallons for my 5 gallon keg

 

[andrewmaixner]

The quick summary: hop utilization will increase a little when the sugar content of the wort decreases, and the opposite holds: more sugar concentration gives slightly less hop bitterness.

A good brewing software will calculate that for you, and even take into account the boiloff changes.
Just put in the volume numbers you are have, and it will calculate the IBUs for you. It's very common to top-up the volume to a desired amount before, and even after, the boil. It does not hurt anything.

 

[Abide]

Ok thanks

 

[flars]

A 6 gallon recipe boiled down to 4.5 gallons will give you more concentrated flavors and a higher OG than intended for the recipe. May taste okay this way or could be or it could be a little over whelming. Depends upon the recipe.

 

[ncbrewer]

Boiling the full batch volume plus estimated boil-off is fine - maybe even preferred. In your case, if you were supposed to have 6 gallons to the fermenter, you can top off with water. If the water has chlorine, treat it with campden to prevent off flavors. (Hopefully, you treated the original boil water as well if it's chlorinated.) Be aware that the traditional bitterness formulas show hop utilization increases in a more dilute boil, so you might have to reduce hops to compensate. That theory is being challenged in recent years, and I haven't seen anything that looks like a definite answer yet. I hope this helps.

 

[mredge73]

Figure out what you want your final volume to be and work backwards.
So if you want 5 gallons as your final volume and know you boil off 1.25 then start with 6.25.
Don't forget trub/system loss as well, this can be .25 - .5 gallons depending on hop absorption. I would start with 6.5 gallons and see how that goes.

Always design your recipe for what you want your final volume to be + your trub/system loss.
I know I loose at least .1 gallons per oz of hops to system/trub losss so my recipes are adjusted for that.
I know my boil off is 1.25 per hour so my starting volume is adjusted for that.

 

[Abide]

I do like my stouts bold if that is what your talking about when you say overwhelming

 

[flars]

I do like my stouts bold if that is what your talking about when you say overwhelming

If you like your stouts bold you're probably okay. Someone else may be overwhelmed.

 

[Abide]

Thanks so much for your response. So it's been in fermentation for just over a week I check the gravity and out of the sample tasted it I got to say I was shocked on the flavor it already had happy but shocked. My concern now is that if it already taste like this that it might be over powered later what would I mess up if I added water now. Thanks for the help