Mash Rest / Infusion Temperature

Work out how much boiling water to add to hit your next mash rest temperature.

Current mash temperature

Target rest temperature

Grain weight

Mash water volume

Infusion water temperature

Leave empty for boiling water (100 °C).

Mash tun heat capacity

Water-equivalent volume of your tun, always in liters. Leave 0 if the tun is preheated.

Infusion water to add

1.59 L

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How this calculator works

For infusion step mashes, this calculator estimates how much hot water to add to move from one rest temperature to the next.

It treats the current mash as a thermal mass made up of grain, existing mash water and optional tun heat capacity.

The required addition depends on the current rest, target rest, infusion water temperature and how much room is left in the mash tun.

Measure the actual infusion-water temperature right before adding it; transfer losses can be larger than expected.
Plan the full mash schedule up front so later infusions do not make the mash too thin or exceed tun capacity.