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If you’re using our recipe page, you’ll shortly not need to worry about this calculator as you’ll be able to work it out from your recipe.

If you’re doing a single step mash with a mash out, you’ll not need this calculator. If you’re step mashing in your mash tun, this is what you’re looking for.

You’ll need to enter the following data:

  • Weight of Grains: the total grains in your mash tun
  • Mash Thickness: the current thickness of your mash - how many litres you added to the current mashing step/the weight of grains.
  • Mash Tun Deadspace: all the hidden/wasted space in your mash tun
  • Mash Tun Equivalent Water Volume: the amount of water equivalent of your mash tun. You can work this figure out in the mash tun calibrate page.
  • Current Temperature: the current step temperature
  • Target Temperature: the target step temperature

You need to add only one of these as you’re calculating either the amount of water (at a specified temperature) to add, or the temperature of the water (of a specified volume) to add:

  • Water Temperature: the temperature of the water you’re adding
  • Step Volume: the volume of the step you’re adding

The Results

  • Volume of Mash Step Water Needed: how much water you need to add to the tun (when you’ve specified Water Temperature above) to achieve the target temperature.
  • Step Water Temp: how hot the water needs to be (when you’ve specified the Step Volume) to achieve the target temperature.
  • Volume Equivalent in Tun: how much volume is in your tun after the addition. Useful in understanding whether you’ve exceeded it’s capacity.


  • Add mash step water volume calculator to recipe.

©2024 James Torr