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Full boil starting volume

I’m finally taking the plunge into home brewing and just ordered an extract kit. I’ve heard that the best practice is to do a full wort boil, rather than topping off with additional water after creating a concentrated wort. My question is, is there a general rule for how much water you should start with to arrive at 5 gallons following a full boil, accounting for evaporation during the boil?


If you want to net 5 gallons of finished beer, you need to shoot for 5.5 gallons into the fermenter. For a 60 minute boil, you should shoot for a starting volume of about 6.5 gallons. Keep good notes so if you are off a little, you can adjust on the next batch. Eventually, you will get to know your system quite well.

Greg is right. Additional items for consideration are how hard of a boil you have and the diameter of your pot (the larger the diameter the more boils off due to more surface area). If you boil off too much you can always add some water to top it off. Just remember to mix it well before taking your hydrometer reading. One of the benefits of a full boil is you’ll get better utilization of your hops due to a lower gravity of the wort. If you buy kits look at their directions, especially for bitter beers. If they suggest a partial boil then they have the amount of the bittering hops adjusted for the IBU they are shooting for. If you do a full boil you will end up with a higher IBU. May not matter all that much but it gives you an idea of the science behind it. Many recipes/kits have steeping grains. When you steep them be sure to just use a couple of gallons (or the recipe directions), then when they’re done add your malt & more water. The reason is the PH of the wort may be too high if you steep the grain in the full 6.5 gallons. Hi PH will cause astringency and that’s not desirable, trust me… Cheers, and happy brewing!!!

Many thanks guys! You anticipated my follow-up questions too. Extremely helpful.

Important question. What are you boiling on? Stove top or propane burner?

It’s difficult to do a full wort boil on a stove top as most ranges will not generate enough BTUs to achieve a good hard boil. I use a propane burner with a wide mouth 10 gallon aluminum pot. I usually collect about 7.5 gallons of wort for a 75-minute boil to get to 5.5 gallons

I did a full boil on two burners for 5-6 years. No problem boiling, but the heat and weight for that length of time is hard on the burners (electric). Propane is the way to go. 6.5 pre boil at 60 mins worked for me. Like Greg said, systems vary, so keep good notes.

I’ll be brewing in a 10 gal. BoilerMaker over propane burner. Today is the big day!

Sounds like you are all set, good luck and have fun. Wish I were brewing today, the wife and kids are home and I’m here at work thinking about brewing.

I’m happy to report that everything basically went as expected. My procedure was:

  1. Steep the specialty grains for 20 minutes in 2.5 gal per the kit instructions
  2. Bring to a boil
  3. Add the extract
  4. Fill kettle to 6.5 gal.
  5. Bring to a boil and continue per kit instructions

I considered simplifying this a little by adding extract after filling to 6.5 gallons, but I felt I should follow kit instructions (apart from my one planned deviation) since this was my first dance.

Total yield was 5 gallons, so I had to top off with 2 quarts to reach target volume in the primary. OG was on the money at 1045.

Next time I’ll go with 7 gallons in the boil. Time to start planning the next brew!

Gota love it when a plan comes to fruition. After steeping you can add the LME/DME and then add the water to the starting boil volume. Once it boils and goes through the hot break (foam & burner control) you can add your boiling hops (watch for foam again) & then start the timer. Cheers!!!

hamiltont - Do you mean that the water does not need to boil prior to adding the extract?

[quote=“kcbeersnob”]hamiltont - Do you mean that the water does not need to boil prior to adding the extract?[/quote]That is true. It just helps if it is warm (or hot) so that the extract dissolves easier. You don’t want it to lay on the bottom of the pot and scorch.

Yep. Pour the LME/DME in & stir it up real good before you put the heat to it. Burnt LME/DME beer is not good. Cheers!!!

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