Mash and Sparge Water Calculator

Mash Tun Specifics

Weight of Mash Tun (lbs)
Thermal Mass (btu/lb°F)

Brewing System Losses

Boil Kettle Loss (gal)
Lauter Tun Loss (gal)
Mash Tun Loss (gal)
Fermentation Tank Loss (gal)

Measured Constants

Boiloff per Hour (%/hr)
Wort Cooling Shrinkage (%)
Grain Absorption (gal/lb)

Recipe Specifics

Batch Size (gal)
Grain Bill (lbs)
Mash Thickness (qts/lb)
Boil Time (mins)
Grain Temperature (F)
Target Mash Temperature (F)

Calculated Results

Total Water Needed (gal)
Strike Water Needed (qts)
Sparge Water Needed (gal)
Strike Temperature (F)
Grain Absorption (gal)
Pre-Boil Wort Produced (gal)

Thanks for using the Powers Home Brewery online calculators. You might also be interested in our free full-featured Brewer’s Recipe Calculator (A home brewer’s favorite since 2005).


The tool above is designed to help calculate the required water quantities for the creation of a given recipe based upon grain quantities, system temperatures, and brewing system losses. The calculator will return the same water quantity results as the full-featured Brewer’s Recipe Calculator without having to enter all the recipe’s ingredients, etc…

To begin using the calculator, you must first enter some information regarding your brewing setup.  The following elements will be essential in correctly calculating your brewing information:

  • Weight of Mash Tun — The weight of the mash tun is required to determine the heat absorption of the mash tun during mash-in. If you preheat your mash tun, this value doesn’t matter.
  • Mash Tun Thermal Mass — This value may require some experimentation to obtain. It is used to determine the amount of heat absorbed by the mash tun during mash-in. A value of .3 is suitable for a Rubbermaid Cooler based mash tun. If you preheat your mash tun with hot water before the mash, use a value of 0 for this particular variable.
  • Boil Kettle Loss — This number refers to the amount of liquid and trub that is left in the bottom of your brew kettle at the end of your boil.
  • Mash Tun Loss — This is the amount of liquid lost to the bottom of the mash tun due to the height of the drainage spigot.
  • Lauter Tun Loss — This is the amount of liquid lost to the bottom of the lauter tun due to the height of the drainage spigot. Since I pump my sparge water through the heat exchange coil on the way to the mash tun, I include the volume of liquid lost to the coil in this quantity as well.
  • Fermentation Tank Loss — This figure refers to the quantity of liquid lost in the bottom of the fermentation tank due to the settling of yeast, yeast dumping, or all around beer loss.
  • Percent Boiloff Per Hour — This amount can vary depending upon your system and how vigorous a boil you are able to achieve. It usually ranges from 9 to 15 percent. My system usually experiences an evaporation rate of about 9%. This is an important figure that may require repeated experimentation in order to determine.
  • Shrinkage Due to Cooling — This value is usually about 4% and is the reduction in volume of your beer from the cooling process that occurs prior to yeast pitching.
  • Grain Absorption Constant — This can vary anywhere between .1 and .2 gallons of water per pound. Different grain crushes can cause different absorption rates.
  • Batch Size — This is simply the final volume of beer (not including fermentation tank loss) you wish to produce based upon the recipe you are following or creating.
  • Mash Thickness — This is the number of quarts of water per pound of grain that is going to be used for the mash. Generally speaking, a thinner mash will lead to a drier beer with a slightly higher alcohol content. A thicker mash usually results in a sweeter beer that has a lower alcohol level. I prefer to use a value of 1.2 quarts of water per pound of grain.
  • Boil Time — This is dependant upon your particular recipe. The boil time is typically between 60 and 90 minutes. The longer your boil, the more liquid you will need in order to achieve your final beer volume.
  • Grain Temperature — Measure the temperature of your grains before you begin brewing. This helps to determine the proper strike water temperature. When the strike water and grain are mixed together, the end result should be very close to your recipe’s required initial mash temperature.
  • Mash Temperature — Since I normally do a single infusion mash, this value is usually the saccharification rest temperature. A higher temperature usually results in a sweeter, less fermentable wort while a lower temperature will result in a drier beer with a higher alcohol content. Much time can be spent determining the proper mashing temperatures for grain. For my mashes, I prefer to use an initial mash temperature between 153 to 157 degrees. Since my system is a recirculating mash system, I do not have to worry about calculating additional mash step infusion temperatures if I choose to use an initial protein rest of 122 degrees. I just set a new temperature on my mash controller and let the system do the work.

Once the above information has been entered, the calculator will determine the proper water quantities needed for your specific recipe as well as the proper water temperature needed to attain your desired mash temperature. It will also note the proper pre-boil volume of liquid you need in order to achieve your desired final beer quantity.