Decoction calculator for estimating volumes and temperatures on your decoction mash. Simply input your information where prompted, and numbers will automatically be calculated below.

Decoction Calculator Notes:

  • Decoction Volume = (Total Mash Volume x (Target Temp – Start Temp ) / (Boil Temp – Start Temp))
  • Noticeable heat loss occurs between steps when using water cooler mash tun! 
    • Adjust 2-6 degrees up on new target temperature, use this calculator to adjust on the fly
  • https://www.rackers.org/calcs.shtml has been taken into account when finding Total Mash Volume
    • Total Mash Volume in quarts = (Mash Weight x (0.078 + (Mash Thickness / 4))*4
  • If doing a Single or Double Decoction, enter same temperature as previous steps
  • If doing longer 15 minute or longer decoctions and/or thinner (soupy liquidy) decoctions, modify decoction equation to include decoction boil off
    • Decoction volume = (Total Mash Volume x (Target Temp – Start Temp) / (Boil Temp – Start Temp))+(Decoction Boil Time x Boil Rate)
  • See below for rest temperature ranges

Mash Temps & Ranges

Enzyme CreatedTemperature RangeIdeal TemperatureIdeal TimeDenatures At
Phytase86ºF – 128ºF95ºF10 minutes140ºF
Beta-Glucanase95ºF – 131ºF113ºF15 minutes140ºF
Peptidase113ºF – 128ºF122ºF20 minutes145ºF
Proteinase122ºF – 138ºF136ºF20 minutes155ºF
Beta-Amylase130ºF – 150ºF148ºF60 minutes160ºF
Alpha-Amylase150ºF – 160ºF158ºF45 minutes170ºF