Mash Infusion
Use this free mash infusion calculator to work out how much boiling water to add when stepping up your mash to the next rest temperature — for example moving from a protein rest to your main saccharification rest.
How to use it
- Note your grain weight and current mash water volume.
- Measure the current mash temperature and decide your next target temperature.
- Check the temperature of the hot water you'll add (usually just off the boil).
- Enter all five values — the calculator tells you exactly how much water to stir in.
Why use step mashing?
Step mashing (moving through multiple rest temperatures) lets you target different enzyme groups — a protein rest at 50–55°C, then a saccharification rest at 65–68°C, for example. Adding hot water is the simplest way to raise the temperature without direct heat, avoiding scorching and giving even, gentle heating throughout the mash.
What if I don't have a large enough kettle to boil extra water?
You don't need to boil a huge amount — usually just a few litres, well off the boil, is enough to raise a full mash by several degrees. Boil it separately in any pan, and stir thoroughly once added to avoid hot spots.
More free home brew calculators
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