Input
How to use this calculator
Enter the grain weight, grain temperature, mash water volume and target mash temperature. The optional mash-tun heat value represents an equivalent volume of water that absorbs heat from the mash. Leave it at zero when you do not have a measured equipment value.
Measure grain and room temperature before dough-in. The water volume must be the volume that will be mixed with the grain, and the target should be the temperature you want after mixing, not the temperature of the kettle.
How the calculation works
The calculation uses Beer Control's mash heat-balance engine: the target temperature is adjusted by the grain thermal contribution and effective water volume, using a grain specific-heat coefficient of 0.40. The optional tun value increases effective thermal mass.
This is a strike estimate, not a guarantee. Grain moisture, heat loss during transfer, mixing time, vessel material and thermometer position all matter. Measure the mash after thorough mixing and correct your next strike temperature from the observed result.
Example calculation
With 5 kg of grain at 20 C, 15 L of mash water, a 67 C target and 0.5 L of equivalent tun heat, the calculator returns a strike temperature above the mash target because the cooler grain absorbs heat.
Understanding the result
Strike temperature is the starting water temperature needed before grain is mixed in. It is normally higher than the target mash temperature. A stable mash temperature supports predictable enzyme activity, but the best correction comes from your own equipment measurements.
Use the first brew as a calibration opportunity. Record strike temperature, dough-in temperature and the temperature after ten minutes. Those observations are more useful than assuming every mash tun has the same heat loss.
Common mistakes
- Entering the target temperature as the strike temperature.
- Forgetting that grain is usually cooler than the target mash.
- Using total batch water instead of mash-in water.
- Adding a tun heat value that was not measured or estimated consistently.
Frequently asked questions
Why is strike water hotter than the mash target?
The grain and mash tun absorb heat, so the starting water must compensate for that thermal loss.
What does tun heat capacity mean here?
It is an optional water-equivalent value describing how much heat the vessel absorbs during dough-in.
Should I trust the first result exactly?
Use it as a starting point, then adjust future brews using measured dough-in temperatures from your equipment.
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