Strike Water Temperature Calculator
Cold grain steals heat, so strike water starts hotter than your mash target. Thicker mash and colder grain need it hotter still.
Strike water temperature is the temperature your infusion water needs to be before you add it to the grain. The cold grain absorbs heat from the water, dropping it to your target mash temperature. Get this wrong and you're mashing too hot or too cold — alpha and beta amylase work at different temperatures, so it matters.
The calculation is simple: more grain relative to water means you need hotter strike water, and colder grain means you need hotter water. The calculator above uses Palmer's heat balance equation, the standard across brewing software. For a step mash, the first rest uses this equation; subsequent rests add boiling water to raise temperature, which the recipe builder handles automatically.
How We Calculate It
Where r is mash thickness in L/kg and 0.41 is the grain/water heat capacity ratio.
The 0.41 constant is the ratio of grain's specific heat capacity to water's (approximately 1.71 kJ/kg·K ÷ 4.18 kJ/kg·K). It tells you how much less heat grain holds compared to water at the same temperature — which is why you need strike water hotter than your target: the grain steals heat.
Target mash temp 67°C, grain at 20°C, thickness 3.0 L/kg:
67 + (0.41 ÷ 3.0) × (67 − 20) = 67 + 0.137 × 47 = 73.4°C
You need strike water at 73.4°C (164.1°F) to land at your 67°C target mash temperature.
Mash Thickness
Mash thickness (the water-to-grain ratio) is how many liters of water you use per kilogram of grain. A typical single infusion mash runs 2.5–4.0 L/kg. Thinner mashes (more water) are more temperature-stable and easier to control. Thicker mashes (less water) can improve efficiency but require more precise strike temperatures.
Grain Temperature
If your grain is stored in a cold garage (5–10°C) versus a warm kitchen (22°C), your strike temperature changes by several degrees. It's worth measuring actual grain temp rather than guessing room temperature — especially in winter. The recipe builder defaults to 20°C (68°F), which is fine for grain stored indoors. Related: how mash temperature shapes fermentability.
How do you calculate strike water temperature?
Palmer's heat balance: T_strike = T_mash + (0.41 ÷ r) × (T_mash − T_grain), where r is mash thickness in L/kg. The 0.41 is grain's heat capacity relative to water.
Why does strike water need to be hotter than the mash?
Grain enters cold and absorbs heat from the water until everything equilibrates. The water has to start above target so the mixture settles at your mash temperature.
What mash thickness should I use?
2.0–2.5 L/kg is a thick, traditional mash; 2.5–3.5 L/kg is the standard single-infusion range; 3.5–4.5 L/kg is thin and typical for brew-in-a-bag. Thinner mashes are more temperature-stable.
Does grain temperature really matter?
Yes — grain at 5–10°C in a cold garage versus 22°C in a warm kitchen can shift the strike temperature by several degrees. Measure it in winter rather than assuming room temperature.
How do I hit later mash steps?
Step mashes raise temperature by infusing boiling water or applying direct heat, which is a different calculation. This covers the initial infusion; the recipe builder handles step infusions automatically.