Brewing Wort: Calculating Boil Length for Desired Gravity

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SUMMARY

This discussion focuses on calculating the boil length required to achieve a desired specific gravity in home brewing. Key parameters include the volume of wort collected, initial specific gravity, anticipated specific gravity post-boil, boiling temperature at 212°F, and an evaporation rate of 20% per hour. The participants emphasize the importance of using a hydrometer for accurate specific gravity measurements, particularly when brewing from scratch. Understanding these calculations can significantly streamline the brewing process.

PREREQUISITES
  • Understanding of home brewing processes, specifically wort collection.
  • Familiarity with specific gravity and its measurement using a hydrometer.
  • Knowledge of evaporation rates and their impact on brewing volume.
  • Basic grasp of the boiling point of water and its relevance in brewing.
NEXT STEPS
  • Research how to calculate boil length based on wort volume and specific gravity.
  • Learn about the effects of evaporation rates on brewing efficiency.
  • Explore advanced hydrometer techniques for measuring specific gravity.
  • Investigate the impact of temperature variations on boiling and evaporation in brewing.
USEFUL FOR

This discussion is beneficial for home brewers, brewing enthusiasts, and anyone interested in optimizing their brewing process through precise calculations of boil length and specific gravity.

Ohio Homebrew
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Hello. I am not quite sure this is the correct place for this question so I will apologize now if it isn't. As a home brewer I mash the malt with hot water and collect the runoff (called wort) which contains the sugars needed for fermentation. Most recipes call for a boil length of either 60 or 90 minutes with an anticipated specific gravity at the end of the boil. My question is this, if I know:

The volume of wort collected in gallons
The specific gravity of the wort before the boil
The anticipated specific gravity post boil
The temperature at which the wort boils, 212° F
An evaporation rate of 20% per hour

How long must the boil be to reach the anticipated specific gravity? I'm not too worried about humidity, ambient temperature, elevation, or other external factors, but knowing this could make planning a brew day much easier.

Thank You,

Tom Dible
 
Last edited:
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i don't know, Buckeye Brother
bnut i'll be there to sample any runs...
since we don't have a college ball team these days..

where's Woody?
 
Hi Tom,

I have attempted a few brews before. I have never tried calculate boiling time and such.
I basically use a hydrometer to find specific gravity. I find this the most accurate method considering all the variables, especially brewing from 'scratch'.

I have a friend that is a brewer in a commercial micro brewery. His test for the wort is a pipette of several mm to taste, and hydrometer.

LOL, I think, sometimes the more random variables added into the brew only tend to make it more interesting.

Yes, I also would like to be there to have a 'wee' sample of your run.
 

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